644022460 has 24 divisors (see below), whose sum is σ = 1365842016. Its totient is φ = 255057600.

The previous prime is 644022433. The next prime is 644022473. The reversal of 644022460 is 64220446.

It is a congruent number.

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, 157392 + ... + 161431.

It is an arithmetic number, because the mean of its divisors is an integer number (56910084).

Almost surely, 2^644022460 is an apocalyptic number.

It is an amenable number.

644022460 is an abundant number, since it is smaller than the sum of its proper divisors (721819556).

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

644022460 is a wasteful number, since it uses less digits than its factorization.

644022460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318933 (or 318931 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 644022460 is about 25377.5976010339. The cubic root of 644022460 is about 863.5755499057.

It can be divided in two parts, 6440 and 22460, that added together give a square (28900 = 170²).

The spelling of 644022460 in words is "six hundred forty-four million, twenty-two thousand, four hundred sixty".