85639702721 has 2 divisors, whose sum is σ = 85639702722. Its totient is φ = 85639702720.

The previous prime is 85639702711. The next prime is 85639702769. The reversal of 85639702721 is 12720793658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80326896400 + 5312806321 = 283420^2 + 72889^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-85639702721 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 85639702721.

It is not a weakly prime, because it can be changed into another prime (85639702711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42819851360 + 42819851361.

It is an arithmetic number, because the mean of its divisors is an integer number (42819851361).

Almost surely, 2^85639702721 is an apocalyptic number.

It is an amenable number.

85639702721 is a deficient number, since it is larger than the sum of its proper divisors (1).

85639702721 is an equidigital number, since it uses as much as digits as its factorization.

85639702721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1270080, while the sum is 50.

The spelling of 85639702721 in words is "eighty-five billion, six hundred thirty-nine million, seven hundred two thousand, seven hundred twenty-one".