644620357025 has 12 divisors (see below), whose sum is σ = 799432741884. Its totient is φ = 515629512000.

The previous prime is 644620357021. The next prime is 644620357033. The reversal of 644620357025 is 520753026446.

It can be written as a sum of positive squares in 6 ways, for example, as 85713101824 + 558907255201 = 292768^2 + 747601^2 .

It is not a de Polignac number, because 644620357025 - 2² = 644620357021 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644620357021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1471946 + ... + 1858995.

It is an arithmetic number, because the mean of its divisors is an integer number (66619395157).

Almost surely, 2^644620357025 is an apocalyptic number.

It is an amenable number.

644620357025 is a deficient number, since it is larger than the sum of its proper divisors (154812384859).

644620357025 is a wasteful number, since it uses less digits than its factorization.

644620357025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3338692 (or 3338687 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 44.

The spelling of 644620357025 in words is "six hundred forty-four billion, six hundred twenty million, three hundred fifty-seven thousand, twenty-five".