638992 has 10 divisors (see below), whose sum is σ = 1238078. Its totient is φ = 319488.

The previous prime is 638977. The next prime is 638993. The reversal of 638992 is 299836.

638992 is nontrivially palindromic in base 3.

It can be written as a sum of positive squares in only one way, i.e., 614656 + 24336 = 784^2 + 156^2 .

It is not an unprimeable number, because it can be changed into a prime (638993) by changing a digit.

638992 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19953 + ... + 19984.

2⁶³⁸⁹⁹² is an apocalyptic number.

It is an amenable number.

638992 is a deficient number, since it is larger than the sum of its proper divisors (599086).

638992 is a wasteful number, since it uses less digits than its factorization.

638992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39945 (or 39939 counting only the distinct ones).

The product of its digits is 23328, while the sum is 37.

The square root of 638992 is about 799.3697517420. The cubic root of 638992 is about 86.1321206993.

The spelling of 638992 in words is "six hundred thirty-eight thousand, nine hundred ninety-two".