638986 has 16 divisors (see below), whose sum is σ = 1036800. Its totient is φ = 294448.

The previous prime is 638977. The next prime is 638993. The reversal of 638986 is 689836.

It is an unprimeable number.

638986 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1095 + ... + 1573.

It is an arithmetic number, because the mean of its divisors is an integer number (64800).

2⁶³⁸⁹⁸⁶ is an apocalyptic number.

638986 is a deficient number, since it is larger than the sum of its proper divisors (397814).

638986 is a wasteful number, since it uses less digits than its factorization.

638986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533.

The product of its digits is 62208, while the sum is 40.

The square root of 638986 is about 799.3659987765. The cubic root of 638986 is about 86.1318511110.

The spelling of 638986 in words is "six hundred thirty-eight thousand, nine hundred eighty-six".