85135721 has 18 divisors (see below), whose sum is σ = 96598698. Its totient is φ = 74932000.

The previous prime is 85135691. The next prime is 85135723. The reversal of 85135721 is 12753158.

It can be written as a sum of positive squares in only one way, i.e., 51912025 + 33223696 = 7205^2 + 5764^2 .

It is not a de Polignac number, because 85135721 - 2¹⁰ = 85134697 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85135723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 649826 + ... + 649956.

Almost surely, 2^85135721 is an apocalyptic number.

It is an amenable number.

85135721 is a deficient number, since it is larger than the sum of its proper divisors (11462977).

85135721 is a wasteful number, since it uses less digits than its factorization.

85135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325 (or 183 counting only the distinct ones).

The product of its digits is 8400, while the sum is 32.

The square root of 85135721 is about 9226.9020261407. The cubic root of 85135721 is about 439.9168592910.

Adding to 85135721 its reverse (12753158), we get a palindrome (97888879).

The spelling of 85135721 in words is "eighty-five million, one hundred thirty-five thousand, seven hundred twenty-one".