638739 has 16 divisors (see below), whose sum is σ = 971040. Its totient is φ = 414720.

The previous prime is 638719. The next prime is 638767. The reversal of 638739 is 937836.

It is not a de Polignac number, because 638739 - 2¹² = 634643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638719) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 819 + ... + 1395.

It is an arithmetic number, because the mean of its divisors is an integer number (60690).

2⁶³⁸⁷³⁹ is an apocalyptic number.

638739 is a deficient number, since it is larger than the sum of its proper divisors (332301).

638739 is a wasteful number, since it uses less digits than its factorization.

638739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627 (or 621 counting only the distinct ones).

The product of its digits is 27216, while the sum is 36.

The square root of 638739 is about 799.2114864039. The cubic root of 638739 is about 86.1207515934.

The spelling of 638739 in words is "six hundred thirty-eight thousand, seven hundred thirty-nine".