691431231 has 16 divisors (see below), whose sum is σ = 931138560. Its totient is φ = 456356160.

The previous prime is 691431227. The next prime is 691431263. The reversal of 691431231 is 132134196.

It is not a de Polignac number, because 691431231 - 2² = 691431227 is a prime.

It is a super-2 number, since 2×691431231² = 956154294404350722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691431211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 186411 + ... + 190083.

It is an arithmetic number, because the mean of its divisors is an integer number (58196160).

Almost surely, 2^691431231 is an apocalyptic number.

691431231 is a deficient number, since it is larger than the sum of its proper divisors (239707329).

691431231 is a wasteful number, since it uses less digits than its factorization.

691431231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4286.

The product of its digits is 3888, while the sum is 30.

The square root of 691431231 is about 26295.0799770603. The cubic root of 691431231 is about 884.2661438534.

The spelling of 691431231 in words is "six hundred ninety-one million, four hundred thirty-one thousand, two hundred thirty-one".