644720604 has 24 divisors (see below), whose sum is σ = 1641107328. Its totient is φ = 195369840.

The previous prime is 644720603. The next prime is 644720641. The reversal of 644720604 is 406027446.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644720603) 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, 2441992 + ... + 2442255.

It is an arithmetic number, because the mean of its divisors is an integer number (68379472).

Almost surely, 2^644720604 is an apocalyptic number.

It is an amenable number.

644720604 is an abundant number, since it is smaller than the sum of its proper divisors (996386724).

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

644720604 is a wasteful number, since it uses less digits than its factorization.

644720604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4884265 (or 4884263 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 33.

The square root of 644720604 is about 25391.3489992162. The cubic root of 644720604 is about 863.8874864203.

The spelling of 644720604 in words is "six hundred forty-four million, seven hundred twenty thousand, six hundred four".