644779896 has 32 divisors (see below), whose sum is σ = 1696790400. Its totient is φ = 203614560.

The previous prime is 644779853. The next prime is 644779903. The reversal of 644779896 is 698977446.

It is a super-2 number, since 2×644779896² = 831482228571541632, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 706540 + ... + 707451.

It is an arithmetic number, because the mean of its divisors is an integer number (53024700).

Almost surely, 2^644779896 is an apocalyptic number.

It is an amenable number.

644779896 is an abundant number, since it is smaller than the sum of its proper divisors (1052010504).

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

644779896 is a wasteful number, since it uses less digits than its factorization.

644779896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1414019 (or 1414015 counting only the distinct ones).

The product of its digits is 18289152, while the sum is 60.

The square root of 644779896 is about 25392.5165353889. The cubic root of 644779896 is about 863.9139681999.

The spelling of 644779896 in words is "six hundred forty-four million, seven hundred seventy-nine thousand, eight hundred ninety-six".