638736 has 40 divisors (see below), whose sum is σ = 1886784. Its totient is φ = 182400.

The previous prime is 638719. The next prime is 638767. The reversal of 638736 is 637836.

It is a happy number.

638736 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 638697 and 638706.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 638736.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 615 + ... + 1286.

2⁶³⁸⁷³⁶ is an apocalyptic number.

It is an amenable number.

638736 is an abundant number, since it is smaller than the sum of its proper divisors (1248048).

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

638736 is a wasteful number, since it uses less digits than its factorization.

638736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919 (or 1913 counting only the distinct ones).

The product of its digits is 18144, while the sum is 33.

The square root of 638736 is about 799.2096095518. The cubic root of 638736 is about 86.1206167639.

Subtracting from 638736 its reverse (637836), we obtain a square (900 = 30²).

The spelling of 638736 in words is "six hundred thirty-eight thousand, seven hundred thirty-six".