85729072921 has 4 divisors (see below), whose sum is σ = 85879739700. Its totient is φ = 85578406144.

The previous prime is 85729072889. The next prime is 85729072939. The reversal of 85729072921 is 12927092758.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18409062400 + 67320010521 = 135680^2 + 259461^2 .

It is a cyclic number.

It is not a de Polignac number, because 85729072921 - 2⁵ = 85729072889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85729072321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75332536 + ... + 75333673.

It is an arithmetic number, because the mean of its divisors is an integer number (21469934925).

Almost surely, 2^85729072921 is an apocalyptic number.

It is an amenable number.

85729072921 is a deficient number, since it is larger than the sum of its proper divisors (150666779).

85729072921 is a wasteful number, since it uses less digits than its factorization.

85729072921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150666778.

The product of its (nonzero) digits is 1270080, while the sum is 52.

The spelling of 85729072921 in words is "eighty-five billion, seven hundred twenty-nine million, seventy-two thousand, nine hundred twenty-one".