644992905 has 32 divisors (see below), whose sum is σ = 1111587840. Its totient is φ = 318306240.

The previous prime is 644992883. The next prime is 644992921. The reversal of 644992905 is 509299446.

It is not a de Polignac number, because 644992905 - 2¹⁶ = 644927369 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14061 + ... + 38570.

It is an arithmetic number, because the mean of its divisors is an integer number (34737120).

Almost surely, 2^644992905 is an apocalyptic number.

It is an amenable number.

644992905 is a deficient number, since it is larger than the sum of its proper divisors (466594935).

644992905 is a wasteful number, since it uses less digits than its factorization.

644992905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52701.

The product of its (nonzero) digits is 699840, while the sum is 48.

The square root of 644992905 is about 25396.7105153404. The cubic root of 644992905 is about 864.0090917146.

The spelling of 644992905 in words is "six hundred forty-four million, nine hundred ninety-two thousand, nine hundred five".