644431264622456 has 16 divisors (see below), whose sum is σ = 1208308895298600. Its totient is φ = 322215559209504.

The previous prime is 644431264622441. The next prime is 644431264622473. The reversal of 644431264622456 is 654226462134446.

It is a junction number, because it is equal to n+sod(n) for n = 644431264622395 and 644431264622404.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53948630 + ... + 64802138.

Almost surely, 2^{644431264622456} is an apocalyptic number.

It is an amenable number.

644431264622456 is a deficient number, since it is larger than the sum of its proper divisors (563877630676144).

644431264622456 is a wasteful number, since it uses less digits than its factorization.

644431264622456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18275438 (or 18275434 counting only the distinct ones).

The product of its digits is 159252480, while the sum is 59.

The spelling of 644431264622456 in words is "six hundred forty-four trillion, four hundred thirty-one billion, two hundred sixty-four million, six hundred twenty-two thousand, four hundred fifty-six".