644846643 has 32 divisors (see below), whose sum is σ = 1149273600. Its totient is φ = 349087968.

The previous prime is 644846611. The next prime is 644846689. The reversal of 644846643 is 346648446.

It is not a de Polignac number, because 644846643 - 2⁵ = 644846611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644846603) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86196 + ... + 93377.

It is an arithmetic number, because the mean of its divisors is an integer number (35914800).

Almost surely, 2^644846643 is an apocalyptic number.

644846643 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

644846643 is a deficient number, since it is larger than the sum of its proper divisors (504426957).

644846643 is a wasteful number, since it uses less digits than its factorization.

644846643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179608 (or 179602 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 45.

The square root of 644846643 is about 25393.8308059261. The cubic root of 644846643 is about 863.9437776880.

The spelling of 644846643 in words is "six hundred forty-four million, eight hundred forty-six thousand, six hundred forty-three".