644349868 has 6 divisors (see below), whose sum is σ = 1127612276. Its totient is φ = 322174932.

The previous prime is 644349859. The next prime is 644349877. The reversal of 644349868 is 868943446.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (644349859) and next prime (644349877).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80543730 + ... + 80543737.

Almost surely, 2^644349868 is an apocalyptic number.

It is an amenable number.

644349868 is a deficient number, since it is larger than the sum of its proper divisors (483262408).

644349868 is a wasteful number, since it uses less digits than its factorization.

644349868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161087471 (or 161087469 counting only the distinct ones).

The product of its digits is 3981312, while the sum is 52.

The square root of 644349868 is about 25384.0475101982. The cubic root of 644349868 is about 863.7218665646.

The spelling of 644349868 in words is "six hundred forty-four million, three hundred forty-nine thousand, eight hundred sixty-eight".