644474620 has 12 divisors (see below), whose sum is σ = 1353396744. Its totient is φ = 257789840.

The previous prime is 644474609. The next prime is 644474629. The reversal of 644474620 is 26474446.

It is a self number, because there is not a number n which added to its sum of digits gives 644474620.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644474629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16111846 + ... + 16111885.

It is an arithmetic number, because the mean of its divisors is an integer number (112783062).

Almost surely, 2^644474620 is an apocalyptic number.

It is an amenable number.

644474620 is an abundant number, since it is smaller than the sum of its proper divisors (708922124).

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

644474620 is a wasteful number, since it uses less digits than its factorization.

644474620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32223740 (or 32223738 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 37.

The square root of 644474620 is about 25386.5046826065. The cubic root of 644474620 is about 863.7776044396. Note that the first 3 decimals are identical.

The spelling of 644474620 in words is "six hundred forty-four million, four hundred seventy-four thousand, six hundred twenty".