644239696 has 20 divisors (see below), whose sum is σ = 1248616512. Its totient is φ = 322016096.

The previous prime is 644239693. The next prime is 644239699. The reversal of 644239696 is 696932446.

It is an interprime number because it is at equal distance from previous prime (644239693) and next prime (644239699).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644239693) 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, 78441 + ... + 86263.

Almost surely, 2^644239696 is an apocalyptic number.

It is an amenable number.

644239696 is a deficient number, since it is larger than the sum of its proper divisors (604376816).

644239696 is a wasteful number, since it uses less digits than its factorization.

644239696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12978 (or 12972 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 49.

The square root of 644239696 is about 25381.8773143359. The cubic root of 644239696 is about 863.6726368970.

The spelling of 644239696 in words is "six hundred forty-four million, two hundred thirty-nine thousand, six hundred ninety-six".