644459697 has 12 divisors (see below), whose sum is σ = 1063870080. Its totient is φ = 368262648.

The previous prime is 644459659. The next prime is 644459719. The reversal of 644459697 is 796954446.

It is a happy number.

644459697 is a `hidden beast` number, since 6 + 4 + 44 + 596 + 9 + 7 = 666.

644459697 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-644459697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644459657) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5114697 + ... + 5114822.

It is an arithmetic number, because the mean of its divisors is an integer number (88655840).

Almost surely, 2^644459697 is an apocalyptic number.

It is an amenable number.

644459697 is a deficient number, since it is larger than the sum of its proper divisors (419410383).

644459697 is a wasteful number, since it uses less digits than its factorization.

644459697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10229532 (or 10229529 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 54.

The square root of 644459697 is about 25386.2107649015. The cubic root of 644459697 is about 863.7709373797.

The spelling of 644459697 in words is "six hundred forty-four million, four hundred fifty-nine thousand, six hundred ninety-seven".