400 (number)
natural number
400 (four hundred) is the natural number following 399 and preceding 401.
Mathematical properties
A circle is divided into 400 grads.
The number 400 equals 1111 in base 7.
Integers from 401 to 499
400s
401
401 is the 79th prime number. It is a Ramanujan prime, a Pythagorean prime, a Chen prime, a super-prime, and an Irregular prime. It is also a Tetranacci number, a zero of Mertens function, and a member of the Mian–Chowla sequence. There are 401 connected, planar, Eulerian graphs with a total of 9 vertices.
402
402 = 2 × 3 × 67. It is a sphenic number, a nontotient and a Harshad number. There are 402 graphs with 8 nodes and 9 edges.
“400 (number)” enters the record as natural number. Crown Archives preserves that source wording while asking what number and natural can confirm, complicate or overturn.
Why this record matters
“400 (number)” is worth following because a concise public description often conceals a longer documentary argument. Here, number and natural provides the most credible route into that argument.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 23, 2026. The linked authority identifier is Q1535396. The Library of Congress control number is sh98001718. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1111.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
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Three-step research path
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Questions for further research
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This entry incorporates text from “400 (number)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.