639139 has 4 divisors (see below), whose sum is σ = 642160. Its totient is φ = 636120.

The previous prime is 639137. The next prime is 639143. The reversal of 639139 is 931936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639139 - 2¹ = 639137 is a prime.

It is a super-2 number, since 2×639139² = 816997322642, which contains 22 as substring.

It is a Duffinian number.

639139 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 639139.

It is not an unprimeable number, because it can be changed into a prime (639137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1167 + ... + 1624.

It is an arithmetic number, because the mean of its divisors is an integer number (160540).

2⁶³⁹¹³⁹ is an apocalyptic number.

639139 is a deficient number, since it is larger than the sum of its proper divisors (3021).

639139 is a wasteful number, since it uses less digits than its factorization.

639139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3020.

The product of its digits is 4374, while the sum is 31.

The square root of 639139 is about 799.4616938916. The cubic root of 639139 is about 86.1387250861.

The spelling of 639139 in words is "six hundred thirty-nine thousand, one hundred thirty-nine".