85578721 has 4 divisors (see below), whose sum is σ = 85633200. Its totient is φ = 85524244.

The previous prime is 85578673. The next prime is 85578737. The reversal of 85578721 is 12787558.

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 a cyclic number.

It is not a de Polignac number, because 85578721 - 2⁷ = 85578593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85578761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24811 + ... + 28048.

It is an arithmetic number, because the mean of its divisors is an integer number (21408300).

Almost surely, 2^85578721 is an apocalyptic number.

It is an amenable number.

85578721 is a deficient number, since it is larger than the sum of its proper divisors (54479).

85578721 is a wasteful number, since it uses less digits than its factorization.

85578721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54478.

The product of its digits is 156800, while the sum is 43.

The square root of 85578721 is about 9250.8767692581. The cubic root of 85578721 is about 440.6785690182.

The spelling of 85578721 in words is "eighty-five million, five hundred seventy-eight thousand, seven hundred twenty-one".