639408 has 80 divisors (see below), whose sum is σ = 2071296. Its totient is φ = 165120.

The previous prime is 639391. The next prime is 639433. The reversal of 639408 is 804936.

It is a congruent number.

It is an unprimeable number.

639408 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 15 ways as a sum of consecutive naturals, for example, 3610 + ... + 3782.

2⁶³⁹⁴⁰⁸ is an apocalyptic number.

639408 is the 462-nd octagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1035648).

639408 is an abundant number, since it is smaller than the sum of its proper divisors (1431888).

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

639408 is a wasteful number, since it uses less digits than its factorization.

639408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 639408 is about 799.6299143979. The cubic root of 639408 is about 86.1508080430.

It can be divided in two parts, 63 and 9408, that multiplied together give a cube (592704 = 84³).

The spelling of 639408 in words is "six hundred thirty-nine thousand, four hundred eight".