644042260 has 48 divisors (see below), whose sum is σ = 1367122176. Its totient is φ = 254846592.

The previous prime is 644042249. The next prime is 644042291. The reversal of 644042260 is 62240446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1390789 + ... + 1391251.

It is an arithmetic number, because the mean of its divisors is an integer number (28481712).

Almost surely, 2^644042260 is an apocalyptic number.

It is an amenable number.

644042260 is an abundant number, since it is smaller than the sum of its proper divisors (723079916).

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

644042260 is a wasteful number, since it uses less digits than its factorization.

644042260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072 (or 1070 counting only the distinct ones).

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

The square root of 644042260 is about 25377.9877058840. The cubic root of 644042260 is about 863.5843998148.

The spelling of 644042260 in words is "six hundred forty-four million, forty-two thousand, two hundred sixty".