83845572721 has 9 divisors (see below), whose sum is σ = 89073017761. Its totient is φ = 78908847232.

The previous prime is 83845572719. The next prime is 83845572737. The reversal of 83845572721 is 12727554838.

It is a happy number.

The square root of 83845572721 is 289561.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 579121 + 83844993600 = 761^2 + 289560^2 .

It is not a de Polignac number, because 83845572721 - 2¹ = 83845572719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (83845572791) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4914021 + ... + 4931053.

Almost surely, 2^83845572721 is an apocalyptic number.

83845572721 is the 289561-st square number.

83845572721 is the 144781-st centered octagonal number.

It is an amenable number.

83845572721 is a deficient number, since it is larger than the sum of its proper divisors (5227445040).

83845572721 is an frugal number, since it uses more digits than its factorization.

83845572721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34100 (or 17050 counting only the distinct ones).

The product of its digits is 3763200, while the sum is 52.

The spelling of 83845572721 in words is "eighty-three billion, eight hundred forty-five million, five hundred seventy-two thousand, seven hundred twenty-one".