645693631 has 12 divisors (see below), whose sum is σ = 710357256. Its totient is φ = 586475120.

The previous prime is 645693619. The next prime is 645693683. The reversal of 645693631 is 136396546.

It is not a de Polignac number, because 645693631 - 2¹⁵ = 645660863 is a prime.

It is a super-2 number, since 2×645693631² = 833840530227928322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645693611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225696 + ... + 228538.

It is an arithmetic number, because the mean of its divisors is an integer number (59196438).

Almost surely, 2^645693631 is an apocalyptic number.

645693631 is a deficient number, since it is larger than the sum of its proper divisors (64663625).

645693631 is a wasteful number, since it uses less digits than its factorization.

645693631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4742 (or 4731 counting only the distinct ones).

The product of its digits is 349920, while the sum is 43.

The square root of 645693631 is about 25410.5023759862. The cubic root of 645693631 is about 864.3218675156.

The spelling of 645693631 in words is "six hundred forty-five million, six hundred ninety-three thousand, six hundred thirty-one".