639065081 has 4 divisors (see below), whose sum is σ = 639187200. Its totient is φ = 638942964.

The previous prime is 639065027. The next prime is 639065087. The reversal of 639065081 is 180560936.

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 cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639065081 is a prime.

It is a super-2 number, since 2×639065081² = 816808355507073122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639065087) 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, 52841 + ... + 63798.

It is an arithmetic number, because the mean of its divisors is an integer number (159796800).

Almost surely, 2^639065081 is an apocalyptic number.

It is an amenable number.

639065081 is a deficient number, since it is larger than the sum of its proper divisors (122119).

639065081 is a wasteful number, since it uses less digits than its factorization.

639065081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122118.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 639065081 is about 25279.7365690388. The cubic root of 639065081 is about 861.3540419457.

The spelling of 639065081 in words is "six hundred thirty-nine million, sixty-five thousand, eighty-one".