644662730 has 16 divisors (see below), whose sum is σ = 1161717120. Its totient is φ = 257570832.

The previous prime is 644662727. The next prime is 644662741. The reversal of 644662730 is 37266446.

644662730 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 27470 + ... + 45209.

It is an arithmetic number, because the mean of its divisors is an integer number (72607320).

Almost surely, 2^644662730 is an apocalyptic number.

644662730 is a deficient number, since it is larger than the sum of its proper divisors (517054390).

644662730 is a wasteful number, since it uses less digits than its factorization.

644662730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73573.

The product of its (nonzero) digits is 145152, while the sum is 38.

The square root of 644662730 is about 25390.2093335207. The cubic root of 644662730 is about 863.8616364009.

The spelling of 644662730 in words is "six hundred forty-four million, six hundred sixty-two thousand, seven hundred thirty".