644406022 has 16 divisors (see below), whose sum is σ = 1044816192. Its totient is φ = 296317440.

The previous prime is 644405989. The next prime is 644406031. The reversal of 644406022 is 220604446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38683 + ... + 52774.

It is an arithmetic number, because the mean of its divisors is an integer number (65301012).

Almost surely, 2^644406022 is an apocalyptic number.

644406022 is a deficient number, since it is larger than the sum of its proper divisors (400410170).

644406022 is a wasteful number, since it uses less digits than its factorization.

644406022 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91743.

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 644406022 is about 25385.1535744813. The cubic root of 644406022 is about 863.7469564685.

The spelling of 644406022 in words is "six hundred forty-four million, four hundred six thousand, twenty-two".