644387502 has 16 divisors (see below), whose sum is σ = 1405936512. Its totient is φ = 195268920.

The previous prime is 644387479. The next prime is 644387509. The reversal of 644387502 is 205783446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644387509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4881658 + ... + 4881789.

It is an arithmetic number, because the mean of its divisors is an integer number (87871032).

Almost surely, 2^644387502 is an apocalyptic number.

644387502 is an abundant number, since it is smaller than the sum of its proper divisors (761549010).

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

644387502 is a wasteful number, since it uses less digits than its factorization.

644387502 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9763463.

The product of its (nonzero) digits is 161280, while the sum is 39.

The square root of 644387502 is about 25384.7887917154. The cubic root of 644387502 is about 863.7386817958.

The spelling of 644387502 in words is "six hundred forty-four million, three hundred eighty-seven thousand, five hundred two".