644892979 has 8 divisors (see below), whose sum is σ = 651819168. Its totient is φ = 637977600.

The previous prime is 644892971. The next prime is 644893001. The reversal of 644892979 is 979298446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644892979 - 2³ = 644892971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644892971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184819 + ... + 188275.

It is an arithmetic number, because the mean of its divisors is an integer number (81477396).

Almost surely, 2^644892979 is an apocalyptic number.

644892979 is a deficient number, since it is larger than the sum of its proper divisors (6926189).

644892979 is a wasteful number, since it uses less digits than its factorization.

644892979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5405.

The product of its digits is 7838208, while the sum is 58.

The square root of 644892979 is about 25394.7431371140. The cubic root of 644892979 is about 863.9644703289.

The spelling of 644892979 in words is "six hundred forty-four million, eight hundred ninety-two thousand, nine hundred seventy-nine".