1638943944 has 32 divisors (see below), whose sum is σ = 4469847840. Its totient is φ = 496649600.

The previous prime is 1638943937. The next prime is 1638943981. The reversal of 1638943944 is 4493498361.

It is a happy number.

It is a super-2 number, since 2×1638943944² = 5372274503148550272, which contains 22 as substring.

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, 3103797 + ... + 3104324.

It is an arithmetic number, because the mean of its divisors is an integer number (139682745).

Almost surely, 2^1638943944 is an apocalyptic number.

It is an amenable number.

1638943944 is an abundant number, since it is smaller than the sum of its proper divisors (2830903896).

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

1638943944 is a wasteful number, since it uses less digits than its factorization.

1638943944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6208141 (or 6208137 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 51.

The square root of 1638943944 is about 40483.8726408430. The cubic root of 1638943944 is about 1179.0205278141.

The spelling of 1638943944 in words is "one billion, six hundred thirty-eight million, nine hundred forty-three thousand, nine hundred forty-four".