645320631 has 4 divisors (see below), whose sum is σ = 860427512. Its totient is φ = 430213752.

The previous prime is 645320623. The next prime is 645320653. The reversal of 645320631 is 136023546.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 645320631 - 2³ = 645320623 is a prime.

It is a super-2 number, since 2×645320631² = 832877433588476322, 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 (645320671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107553436 + ... + 107553441.

It is an arithmetic number, because the mean of its divisors is an integer number (215106878).

Almost surely, 2^645320631 is an apocalyptic number.

645320631 is a deficient number, since it is larger than the sum of its proper divisors (215106881).

645320631 is a wasteful number, since it uses less digits than its factorization.

645320631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215106880.

The product of its (nonzero) digits is 12960, while the sum is 30.

The square root of 645320631 is about 25403.1618307643. The cubic root of 645320631 is about 864.1554035560.

The spelling of 645320631 in words is "six hundred forty-five million, three hundred twenty thousand, six hundred thirty-one".