644022036 has 48 divisors (see below), whose sum is σ = 1908215680. Its totient is φ = 184006080.

The previous prime is 644021981. The next prime is 644022061. The reversal of 644022036 is 630220446.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 425185 + ... + 426696.

Almost surely, 2^644022036 is an apocalyptic number.

It is an amenable number.

644022036 is an abundant number, since it is smaller than the sum of its proper divisors (1264193644).

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

644022036 is a wasteful number, since it uses less digits than its factorization.

644022036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851901 (or 851893 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

The square root of 644022036 is about 25377.5892472079. The cubic root of 644022036 is about 863.5753603905.

The spelling of 644022036 in words is "six hundred forty-four million, twenty-two thousand, thirty-six".