644043332 has 24 divisors (see below), whose sum is σ = 1178520000. Its totient is φ = 307381536.

The previous prime is 644043311. The next prime is 644043391. The reversal of 644043332 is 233340446.

It is a junction number, because it is equal to n+sod(n) for n = 644043295 and 644043304.

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, 38894 + ... + 52922.

It is an arithmetic number, because the mean of its divisors is an integer number (49105000).

Almost surely, 2^644043332 is an apocalyptic number.

It is an amenable number.

644043332 is a deficient number, since it is larger than the sum of its proper divisors (534476668).

644043332 is a wasteful number, since it uses less digits than its factorization.

644043332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14555 (or 14553 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 29.

The square root of 644043332 is about 25378.0088265411. The cubic root of 644043332 is about 863.5848789562.

Adding to 644043332 its reverse (233340446), we get a palindrome (877383778).

The spelling of 644043332 in words is "six hundred forty-four million, forty-three thousand, three hundred thirty-two".