639664071 has 8 divisors (see below), whose sum is σ = 853082880. Its totient is φ = 426343992.

The previous prime is 639664057. The next prime is 639664111. The reversal of 639664071 is 170466936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 639664071 - 2¹⁵ = 639631303 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639664171) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7941 + ... + 36638.

It is an arithmetic number, because the mean of its divisors is an integer number (106635360).

Almost surely, 2^639664071 is an apocalyptic number.

639664071 is a deficient number, since it is larger than the sum of its proper divisors (213418809).

639664071 is a wasteful number, since it uses less digits than its factorization.

639664071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49365.

The product of its (nonzero) digits is 163296, while the sum is 42.

The square root of 639664071 is about 25291.5810300582. The cubic root of 639664071 is about 861.6230710638.

The spelling of 639664071 in words is "six hundred thirty-nine million, six hundred sixty-four thousand, seventy-one".