645664770631 has 24 divisors (see below), whose sum is σ = 694472437824. Its totient is φ = 600034184640.

The previous prime is 645664770629. The next prime is 645664770649. The reversal of 645664770631 is 136077466546.

It is not a de Polignac number, because 645664770631 - 2¹ = 645664770629 is a prime.

It is a super-2 number, since 2×645664770631² (a number of 24 digits) 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 (645664770671) 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 23 ways as a sum of consecutive naturals, for example, 8174530 + ... + 8253136.

It is an arithmetic number, because the mean of its divisors is an integer number (28936351576).

Almost surely, 2^645664770631 is an apocalyptic number.

645664770631 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

645664770631 is a deficient number, since it is larger than the sum of its proper divisors (48807667193).

645664770631 is a wasteful number, since it uses less digits than its factorization.

645664770631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79079 (or 79060 counting only the distinct ones).

The product of its (nonzero) digits is 15240960, while the sum is 55.

The spelling of 645664770631 in words is "six hundred forty-five billion, six hundred sixty-four million, seven hundred seventy thousand, six hundred thirty-one".