957221721 has 9 divisors (see below), whose sum is σ = 1382787679. Its totient is φ = 638085936.

The previous prime is 957221719. The next prime is 957221731. The reversal of 957221721 is 127122759.

The square root of 957221721 is 30939.

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

It can be written as a sum of positive squares in only one way, i.e., 393824025 + 563397696 = 19845^2 + 23736^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 957221721 - 2¹ = 957221719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (957221701) 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, 87661 + ... + 97973.

Almost surely, 2^957221721 is an apocalyptic number.

957221721 is the 30939-th square number.

957221721 is the 15470-th centered octagonal number.

It is an amenable number.

957221721 is a deficient number, since it is larger than the sum of its proper divisors (425565958).

957221721 is an frugal number, since it uses more digits than its factorization.

957221721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20632 (or 10316 counting only the distinct ones).

The product of its digits is 17640, while the sum is 36.

The cubic root of 957221721 is about 985.5322678317.

Multiplying 957221721 by its sum of digits (36), we get a square (34459981956 = 185634²).

The spelling of 957221721 in words is "nine hundred fifty-seven million, two hundred twenty-one thousand, seven hundred twenty-one".