639129081 has 16 divisors (see below), whose sum is σ = 875508480. Its totient is φ = 414498000.

The previous prime is 639129061. The next prime is 639129091. The reversal of 639129081 is 180921936.

639129081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 639129081 - 2¹⁰ = 639128057 is a prime.

It is a super-2 number, since 2×639129081² = 816971964359809122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639129061) 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, 22510 + ... + 42248.

It is an arithmetic number, because the mean of its divisors is an integer number (54719280).

Almost surely, 2^639129081 is an apocalyptic number.

It is an amenable number.

639129081 is a deficient number, since it is larger than the sum of its proper divisors (236379399).

639129081 is a wasteful number, since it uses less digits than its factorization.

639129081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20036.

The product of its (nonzero) digits is 23328, while the sum is 39.

The square root of 639129081 is about 25281.0023733237. The cubic root of 639129081 is about 861.3827947912.

The spelling of 639129081 in words is "six hundred thirty-nine million, one hundred twenty-nine thousand, eighty-one".