644859013772736 has 280 divisors, whose sum is σ = 2220458578790496. Its totient is φ = 181225014958080.

The previous prime is 644859013772693. The next prime is 644859013772761. The reversal of 644859013772736 is 637277310958446.

644859013772736 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 590 + 1 + 3 + 7 + 7 + 27 + 3 + 6 = 666.

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 polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 143446971 + ... + 147874106.

It is a 1-persistent number, because it is pandigital, but 2⋅644859013772736 = 1289718027545472 is not.

Almost surely, 2^{644859013772736} is an apocalyptic number.

It is an amenable number.

644859013772736 is an abundant number, since it is smaller than the sum of its proper divisors (1575599565017760).

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

644859013772736 is a wasteful number, since it uses less digits than its factorization.

644859013772736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291321169 (or 291321150 counting only the distinct ones).

The product of its (nonzero) digits is 1280240640, while the sum is 72.

The spelling of 644859013772736 in words is "six hundred forty-four trillion, eight hundred fifty-nine billion, thirteen million, seven hundred seventy-two thousand, seven hundred thirty-six".