644731012053440 has 224 divisors, whose sum is σ = 1720400315961600. Its totient is φ = 228593504894976.

The previous prime is 644731012053347. The next prime is 644731012053463. The reversal of 644731012053440 is 44350210137446.

It is a junction number, because it is equal to n+sod(n) for n = 644731012053391 and 644731012053400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20746115 + ... + 41471234.

It is an arithmetic number, because the mean of its divisors is an integer number (7680358553400).

Almost surely, 2^{644731012053440} is an apocalyptic number.

It is an amenable number.

644731012053440 is an abundant number, since it is smaller than the sum of its proper divisors (1075669303908160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644731012053440 is a wasteful number, since it uses less digits than its factorization.

644731012053440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62217479 (or 62217469 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 44.

The spelling of 644731012053440 in words is "six hundred forty-four trillion, seven hundred thirty-one billion, twelve million, fifty-three thousand, four hundred forty".