644751057 has 8 divisors (see below), whose sum is σ = 868014784. Its totient is φ = 425660688.

The previous prime is 644751043. The next prime is 644751089. The reversal of 644751057 is 750157446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644751057 - 2¹⁰ = 644750033 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644751007) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1042978 + ... + 1043595.

It is an arithmetic number, because the mean of its divisors is an integer number (108501848).

Almost surely, 2^644751057 is an apocalyptic number.

It is an amenable number.

644751057 is a deficient number, since it is larger than the sum of its proper divisors (223263727).

644751057 is a wasteful number, since it uses less digits than its factorization.

644751057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2086679.

The product of its (nonzero) digits is 117600, while the sum is 39.

The square root of 644751057 is about 25391.9486648819. The cubic root of 644751057 is about 863.9010879459.

The spelling of 644751057 in words is "six hundred forty-four million, seven hundred fifty-one thousand, fifty-seven".