644851763680 has 24 divisors (see below), whose sum is σ = 1523462292072. Its totient is φ = 257940705408.

The previous prime is 644851763641. The next prime is 644851763683. The reversal of 644851763680 is 86367158446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644851763683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2015161602 + ... + 2015161921.

It is an arithmetic number, because the mean of its divisors is an integer number (63477595503).

Almost surely, 2^644851763680 is an apocalyptic number.

It is an amenable number.

644851763680 is an abundant number, since it is smaller than the sum of its proper divisors (878610528392).

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

644851763680 is a wasteful number, since it uses less digits than its factorization.

644851763680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4030323538 (or 4030323530 counting only the distinct ones).

The product of its (nonzero) digits is 23224320, while the sum is 58.

The spelling of 644851763680 in words is "six hundred forty-four billion, eight hundred fifty-one million, seven hundred sixty-three thousand, six hundred eighty".