85664721 has 4 divisors (see below), whose sum is σ = 114219632. Its totient is φ = 57109812.

The previous prime is 85664713. The next prime is 85664767. The reversal of 85664721 is 12746658.

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 not a de Polignac number, because 85664721 - 2³ = 85664713 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 85664721.

It is not an unprimeable number, because it can be changed into a prime (85664771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14277451 + ... + 14277456.

It is an arithmetic number, because the mean of its divisors is an integer number (28554908).

Almost surely, 2^85664721 is an apocalyptic number.

It is an amenable number.

85664721 is a deficient number, since it is larger than the sum of its proper divisors (28554911).

85664721 is a wasteful number, since it uses less digits than its factorization.

85664721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28554910.

The product of its digits is 80640, while the sum is 39.

The square root of 85664721 is about 9255.5238101363. The cubic root of 85664721 is about 440.8261355651.

The spelling of 85664721 in words is "eighty-five million, six hundred sixty-four thousand, seven hundred twenty-one".