638964 has 18 divisors (see below), whose sum is σ = 1615250. Its totient is φ = 212976.

The previous prime is 638959. The next prime is 638971. The reversal of 638964 is 469836.

It can be written as a sum of positive squares in only one way, i.e., 396900 + 242064 = 630^2 + 492^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 17749 = 638964 / (6 + 3 + 8 + 9 + 6 + 4).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8839 + ... + 8910.

2⁶³⁸⁹⁶⁴ is an apocalyptic number.

It is an amenable number.

638964 is an abundant number, since it is smaller than the sum of its proper divisors (976286).

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

638964 is a wasteful number, since it uses less digits than its factorization.

638964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17759 (or 17754 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 638964 is about 799.3522377525. The cubic root of 638964 is about 86.1308626061.

The spelling of 638964 in words is "six hundred thirty-eight thousand, nine hundred sixty-four".