2156580721 has 3 divisors (see below), whose sum is σ = 2156627161. Its totient is φ = 2156534282.

The previous prime is 2156580709. The next prime is 2156580733. The reversal of 2156580721 is 1270856512.

The square root of 2156580721 is 46439.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (2156580709) and next prime (2156580733).

It is not a de Polignac number, because 2156580721 - 2⁷ = 2156580593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2156580221) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 23220 + ... + 69658.

Almost surely, 2^2156580721 is an apocalyptic number.

2156580721 is the 46439-th square number.

2156580721 is the 23220-th centered octagonal number.

It is an amenable number.

2156580721 is a deficient number, since it is larger than the sum of its proper divisors (46440).

2156580721 is an frugal number, since it uses more digits than its factorization.

2156580721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92878 (or 46439 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 37.

The cubic root of 2156580721 is about 1291.9783599608.

The spelling of 2156580721 in words is "two billion, one hundred fifty-six million, five hundred eighty thousand, seven hundred twenty-one".