644754980 has 24 divisors (see below), whose sum is σ = 1372536312. Its totient is φ = 254368512.

The previous prime is 644754973. The next prime is 644754991. The reversal of 644754980 is 89457446.

644754980 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 210366016 + 434388964 = 14504^2 + 20842^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 219347 + ... + 222266.

It is an arithmetic number, because the mean of its divisors is an integer number (57189013).

Almost surely, 2^644754980 is an apocalyptic number.

It is an amenable number.

644754980 is an abundant number, since it is smaller than the sum of its proper divisors (727781332).

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

644754980 is a wasteful number, since it uses less digits than its factorization.

644754980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441695 (or 441693 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 47.

The square root of 644754980 is about 25392.0259136604. The cubic root of 644754980 is about 863.9028400832.

The spelling of 644754980 in words is "six hundred forty-four million, seven hundred fifty-four thousand, nine hundred eighty".