645610931 has 4 divisors (see below), whose sum is σ = 737841072. Its totient is φ = 553380792.

The previous prime is 645610883. The next prime is 645610949. The reversal of 645610931 is 139016546.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645610931 is a prime.

It is a super-2 number, since 2×645610931² = 833626948453373522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645610891 and 645610900.

It is not an unprimeable number, because it can be changed into a prime (645610631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46115060 + ... + 46115073.

It is an arithmetic number, because the mean of its divisors is an integer number (184460268).

Almost surely, 2^645610931 is an apocalyptic number.

645610931 is a deficient number, since it is larger than the sum of its proper divisors (92230141).

645610931 is an equidigital number, since it uses as much as digits as its factorization.

645610931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92230140.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 645610931 is about 25408.8750439684. The cubic root of 645610931 is about 864.2849653550.

The spelling of 645610931 in words is "six hundred forty-five million, six hundred ten thousand, nine hundred thirty-one".