638986994 has 16 divisors (see below), whose sum is σ = 968552640. Its totient is φ = 316144080.

The previous prime is 638986993. The next prime is 638987023. The reversal of 638986994 is 499689836.

It is not an unprimeable number, because it can be changed into a prime (638986993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 223337 + ... + 226179.

It is an arithmetic number, because the mean of its divisors is an integer number (60534540).

Almost surely, 2^638986994 is an apocalyptic number.

638986994 is a deficient number, since it is larger than the sum of its proper divisors (329565646).

638986994 is a wasteful number, since it uses less digits than its factorization.

638986994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3985.

The product of its digits is 20155392, while the sum is 62.

The square root of 638986994 is about 25278.1920635159. The cubic root of 638986994 is about 861.3189577293.

The spelling of 638986994 in words is "six hundred thirty-eight million, nine hundred eighty-six thousand, nine hundred ninety-four".