639131 has 4 divisors (see below), whose sum is σ = 661200. Its totient is φ = 617064.

The previous prime is 639091. The next prime is 639137. The reversal of 639131 is 131936.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639131 is a prime.

It is a super-2 number, since 2×639131² = 816976870322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 639097 and 639106.

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, 10991 + ... + 11048.

It is an arithmetic number, because the mean of its divisors is an integer number (165300).

2⁶³⁹¹³¹ is an apocalyptic number.

639131 is a deficient number, since it is larger than the sum of its proper divisors (22069).

639131 is a wasteful number, since it uses less digits than its factorization.

639131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22068.

The product of its digits is 486, while the sum is 23.

The square root of 639131 is about 799.4566905092. The cubic root of 639131 is about 86.1383656898.

The spelling of 639131 in words is "six hundred thirty-nine thousand, one hundred thirty-one".