644989446 has 16 divisors (see below), whose sum is σ = 1433310000. Its totient is φ = 214996464.

The previous prime is 644989427. The next prime is 644989451.

It is a happy number.

644989446 is a `hidden beast` number, since 64 + 498 + 94 + 4 + 6 = 666.

644989446 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×644989446² = 832022770902773832, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54), and also a Moran number because the ratio is a prime number: 11944249 = 644989446 / (6 + 4 + 4 + 9 + 8 + 9 + 4 + 4 + 6).

It is a junction number, because it is equal to n+sod(n) for n = 644989392 and 644989401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5972071 + ... + 5972178.

It is an arithmetic number, because the mean of its divisors is an integer number (89581875).

Almost surely, 2^644989446 is an apocalyptic number.

644989446 is an abundant number, since it is smaller than the sum of its proper divisors (788320554).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644989446 is a wasteful number, since it uses less digits than its factorization.

644989446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11944260 (or 11944254 counting only the distinct ones).

The product of its digits is 5971968, while the sum is 54.

The square root of 644989446 is about 25396.6424158785. The cubic root of 644989446 is about 864.0075471949.

The spelling of 644989446 in words is "six hundred forty-four million, nine hundred eighty-nine thousand, four hundred forty-six".