638646 has 8 divisors (see below), whose sum is σ = 1277304. Its totient is φ = 212880.

The previous prime is 638633. The next prime is 638663. The reversal of 638646 is 646836.

It is a sphenic number, since it is the product of 3 distinct primes.

638646 is an admirable number.

It is a congruent number.

It is an unprimeable number.

638646 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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53215 + ... + 53226.

It is an arithmetic number, because the mean of its divisors is an integer number (159663).

2⁶³⁸⁶⁴⁶ is an apocalyptic number.

638646 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

638646 is a wasteful number, since it uses less digits than its factorization.

638646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106446.

The product of its digits is 20736, while the sum is 33.

The square root of 638646 is about 799.1533019390. The cubic root of 638646 is about 86.1165716813.

The spelling of 638646 in words is "six hundred thirty-eight thousand, six hundred forty-six".