639617865 has 16 divisors (see below), whose sum is σ = 1024127808. Its totient is φ = 340883136.

The previous prime is 639617863. The next prime is 639617887. The reversal of 639617865 is 568716936.

It is not a de Polignac number, because 639617865 - 2¹ = 639617863 is a prime.

It is a super-2 number, since 2×639617865² = 818222026454316450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639617863) 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, 7122 + ... + 36468.

It is an arithmetic number, because the mean of its divisors is an integer number (64007988).

Almost surely, 2^639617865 is an apocalyptic number.

It is an amenable number.

639617865 is a deficient number, since it is larger than the sum of its proper divisors (384509943).

639617865 is a wasteful number, since it uses less digits than its factorization.

639617865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30808.

The product of its digits is 1632960, while the sum is 51.

The square root of 639617865 is about 25290.6675475362. The cubic root of 639617865 is about 861.6023241769.

The spelling of 639617865 in words is "six hundred thirty-nine million, six hundred seventeen thousand, eight hundred sixty-five".