644238978024960 has 120 divisors (see below), whose sum is σ = 2231180773192800. Its totient is φ = 171797060800512.

The previous prime is 644238978024959. The next prime is 644238978024979. The reversal of 644238978024960 is 69420879832446.

644238978024960 is a `hidden beast` number, since 6 + 4 + 4 + 238 + 97 + 8 + 0 + 249 + 60 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13980857560 + ... + 13980903639.

It is an arithmetic number, because the mean of its divisors is an integer number (18593173109940).

Almost surely, 2^{644238978024960} is an apocalyptic number.

644238978024960 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644238978024960 is an abundant number, since it is smaller than the sum of its proper divisors (1586941795167840).

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

644238978024960 is a wasteful number, since it uses less digits than its factorization.

644238978024960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27961761228 (or 27961761209 counting only the distinct ones).

The product of its (nonzero) digits is 1003290624, while the sum is 72.

The spelling of 644238978024960 in words is "six hundred forty-four trillion, two hundred thirty-eight billion, nine hundred seventy-eight million, twenty-four thousand, nine hundred sixty".