639129 has 4 divisors (see below), whose sum is σ = 852176. Its totient is φ = 426084.

The previous prime is 639091. The next prime is 639137. The reversal of 639129 is 921936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-639129 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 639096 and 639105.

It is not an unprimeable number, because it can be changed into a prime (639169) 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, 106519 + ... + 106524.

It is an arithmetic number, because the mean of its divisors is an integer number (213044).

2⁶³⁹¹²⁹ is an apocalyptic number.

It is an amenable number.

639129 is a deficient number, since it is larger than the sum of its proper divisors (213047).

639129 is a wasteful number, since it uses less digits than its factorization.

639129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213046.

The product of its digits is 2916, while the sum is 30.

The square root of 639129 is about 799.4554396588. The cubic root of 639129 is about 86.1382758402.

The spelling of 639129 in words is "six hundred thirty-nine thousand, one hundred twenty-nine".