644773251357 has 10 divisors (see below), whose sum is σ = 963179795358. Its totient is φ = 429848834184.

The previous prime is 644773251349. The next prime is 644773251431. The reversal of 644773251357 is 753152377446.

644773251357 is a `hidden beast` number, since 6 + 4 + 4 + 7 + 73 + 2 + 513 + 57 = 666.

It can be written as a sum of positive squares in only one way, i.e., 504638323641 + 140134927716 = 710379^2 + 374346^2 .

It is not a de Polignac number, because 644773251357 - 2³ = 644773251349 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644773251307) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 3980081718 + ... + 3980081879.

Almost surely, 2^644773251357 is an apocalyptic number.

It is an amenable number.

644773251357 is a deficient number, since it is larger than the sum of its proper divisors (318406544001).

644773251357 is an equidigital number, since it uses as much as digits as its factorization.

644773251357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7960163609 (or 7960163600 counting only the distinct ones).

The product of its digits is 14817600, while the sum is 54.

The spelling of 644773251357 in words is "six hundred forty-four billion, seven hundred seventy-three million, two hundred fifty-one thousand, three hundred fifty-seven".