644601828 has 72 divisors (see below), whose sum is σ = 1714490400. Its totient is φ = 187888896.

The previous prime is 644601803. The next prime is 644601857. The reversal of 644601828 is 828106446.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30168 + ... + 46896.

Almost surely, 2^644601828 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 644601828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (857245200).

644601828 is an abundant number, since it is smaller than the sum of its proper divisors (1069888572).

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

644601828 is a wasteful number, since it uses less digits than its factorization.

644601828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16781 (or 16766 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 39.

The square root of 644601828 is about 25389.0099846371. The cubic root of 644601828 is about 863.8344322233.

The spelling of 644601828 in words is "six hundred forty-four million, six hundred one thousand, eight hundred twenty-eight".