691637401 has 45 divisors (see below), whose sum is σ = 925657371. Its totient is φ = 515039616.

The previous prime is 691637371. The next prime is 691637431. The reversal of 691637401 is 104736196.

The square root of 691637401 is 26299.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (691637371) and next prime (691637431).

It can be written as a sum of positive squares in 7 ways, for example, as 210975625 + 480661776 = 14525^2 + 21924^2 .

It is not a de Polignac number, because 691637401 - 2⁷ = 691637273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691637431) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 40684545 + ... + 40684561.

Almost surely, 2^691637401 is an apocalyptic number.

691637401 is the 26299-th square number.

691637401 is the 13150-th centered octagonal number.

It is an amenable number.

691637401 is a deficient number, since it is larger than the sum of its proper divisors (234019970).

691637401 is an frugal number, since it uses more digits than its factorization.

691637401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108 (or 37 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 37.

The cubic root of 691637401 is about 884.3540248676.

The spelling of 691637401 in words is "six hundred ninety-one million, six hundred thirty-seven thousand, four hundred one".