644446591 has 12 divisors (see below), whose sum is σ = 714357072. Its totient is φ = 580160768.

The previous prime is 644446573. The next prime is 644446601. The reversal of 644446591 is 195644446.

It is not a de Polignac number, because 644446591 - 2⁷ = 644446463 is a prime.

It is a super-2 number, since 2×644446591² = 830622817303042562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644446511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41830 + ... + 55123.

It is an arithmetic number, because the mean of its divisors is an integer number (59529756).

Almost surely, 2^644446591 is an apocalyptic number.

644446591 is a deficient number, since it is larger than the sum of its proper divisors (69910481).

644446591 is a wasteful number, since it uses less digits than its factorization.

644446591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97010 (or 96993 counting only the distinct ones).

The product of its digits is 414720, while the sum is 43.

The square root of 644446591 is about 25385.9526313274. The cubic root of 644446591 is about 863.7650820052.

It can be divided in two parts, 6444 and 46591, that added together give a palindrome (53035).

The spelling of 644446591 in words is "six hundred forty-four million, four hundred forty-six thousand, five hundred ninety-one".