644928957 has 12 divisors (see below), whose sum is σ = 932921184. Its totient is φ = 429326280.

The previous prime is 644928937. The next prime is 644928961. The reversal of 644928957 is 759829446.

644928957 is a `hidden beast` number, since 64 + 492 + 8 + 95 + 7 = 666.

It is not a de Polignac number, because 644928957 - 2⁷ = 644928829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644928917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45633 + ... + 58070.

It is an arithmetic number, because the mean of its divisors is an integer number (77743432).

Almost surely, 2^644928957 is an apocalyptic number.

It is an amenable number.

644928957 is a deficient number, since it is larger than the sum of its proper divisors (287992227).

644928957 is a wasteful number, since it uses less digits than its factorization.

644928957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104400 (or 104397 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 54.

The square root of 644928957 is about 25395.4515021883. The cubic root of 644928957 is about 863.9805366307.

The spelling of 644928957 in words is "six hundred forty-four million, nine hundred twenty-eight thousand, nine hundred fifty-seven".