644728392 has 96 divisors (see below), whose sum is σ = 2177023680. Its totient is φ = 167460480.

The previous prime is 644728391. The next prime is 644728423. The reversal of 644728392 is 293827446.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (644728391) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52603 + ... + 63690.

It is an arithmetic number, because the mean of its divisors is an integer number (22677330).

Almost surely, 2^644728392 is an apocalyptic number.

It is an amenable number.

644728392 is an abundant number, since it is smaller than the sum of its proper divisors (1532295288).

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

644728392 is a wasteful number, since it uses less digits than its factorization.

644728392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116323 (or 116316 counting only the distinct ones).

The product of its digits is 580608, while the sum is 45.

The square root of 644728392 is about 25391.5023580725. The cubic root of 644728392 is about 863.8909648928.

The spelling of 644728392 in words is "six hundred forty-four million, seven hundred twenty-eight thousand, three hundred ninety-two".