639542761 has 32 divisors (see below), whose sum is σ = 787707648. Its totient is φ = 510935040.

The previous prime is 639542747. The next prime is 639542773. The reversal of 639542761 is 167245936.

It is not a de Polignac number, because 639542761 - 2⁷ = 639542633 is a prime.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (639542711) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1108105 + ... + 1108681.

It is an arithmetic number, because the mean of its divisors is an integer number (24615864).

Almost surely, 2^639542761 is an apocalyptic number.

It is an amenable number.

639542761 is a deficient number, since it is larger than the sum of its proper divisors (148164887).

639542761 is a wasteful number, since it uses less digits than its factorization.

639542761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 961.

The product of its digits is 272160, while the sum is 43.

The square root of 639542761 is about 25289.1826874654. The cubic root of 639542761 is about 861.5685997104.

The spelling of 639542761 in words is "six hundred thirty-nine million, five hundred forty-two thousand, seven hundred sixty-one".