638658 has 16 divisors (see below), whose sum is σ = 1419360. Its totient is φ = 212868.

The previous prime is 638633. The next prime is 638663. The reversal of 638658 is 856836.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 638658.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5860 + ... + 5967.

It is an arithmetic number, because the mean of its divisors is an integer number (88710).

2⁶³⁸⁶⁵⁸ is an apocalyptic number.

638658 is an abundant number, since it is smaller than the sum of its proper divisors (780702).

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

638658 is a wasteful number, since it uses less digits than its factorization.

638658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11838 (or 11832 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 638658 is about 799.1608098499. The cubic root of 638658 is about 86.1171110476.

It can be divided in two parts, 638 and 658, that added together give a 4-th power (1296 = 6⁴).

The spelling of 638658 in words is "six hundred thirty-eight thousand, six hundred fifty-eight".