644527136 has 48 divisors (see below), whose sum is σ = 1404980640. Its totient is φ = 288583680.

The previous prime is 644527127. The next prime is 644527181. The reversal of 644527136 is 631725446.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 644527136.

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, 9920 + ... + 37248.

It is an arithmetic number, because the mean of its divisors is an integer number (29270430).

Almost surely, 2^644527136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644527136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (702490320).

644527136 is an abundant number, since it is smaller than the sum of its proper divisors (760453504).

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

644527136 is a wasteful number, since it uses less digits than its factorization.

644527136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27417 (or 27409 counting only the distinct ones).

The product of its digits is 120960, while the sum is 38.

The square root of 644527136 is about 25387.5389906151. The cubic root of 644527136 is about 863.8010658820.

The spelling of 644527136 in words is "six hundred forty-four million, five hundred twenty-seven thousand, one hundred thirty-six".