644648444 has 24 divisors (see below), whose sum is σ = 1240393728. Its totient is φ = 290712240.

The previous prime is 644648443. The next prime is 644648461. The reversal of 644648444 is 444846446.

It is a super-2 number, since 2×644648444² = 831143232703242272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a junction number, because it is equal to n+sod(n) for n = 644648395 and 644648404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644648443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52094 + ... + 63269.

It is an arithmetic number, because the mean of its divisors is an integer number (51683072).

Almost surely, 2^644648444 is an apocalyptic number.

It is an amenable number.

644648444 is a deficient number, since it is larger than the sum of its proper divisors (595745284).

644648444 is a wasteful number, since it uses less digits than its factorization.

644648444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115505 (or 115503 counting only the distinct ones).

The product of its digits is 1179648, while the sum is 44.

The square root of 644648444 is about 25389.9280030488. The cubic root of 644648444 is about 863.8552551734.

The spelling of 644648444 in words is "six hundred forty-four million, six hundred forty-eight thousand, four hundred forty-four".