2157961 has 9 divisors (see below), whose sum is σ = 2357589. Its totient is φ = 1974336.

The previous prime is 2157923. The next prime is 2157989. The reversal of 2157961 is 1697512.

The square root of 2157961 is 1469.

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 1610361 + 547600 = 1269^2 + 740^2 .

It is not a de Polignac number, because 2157961 - 2⁷ = 2157833 is a prime.

Its product of digits (3780) is a multiple of the sum of its prime divisors (126).

2157961 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2157901) 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, 19041 + ... + 19153.

2^2157961 is an apocalyptic number.

2157961 is the 1469-th square number.

2157961 is the 735-th centered octagonal number.

It is an amenable number.

2157961 is a deficient number, since it is larger than the sum of its proper divisors (199628).

2157961 is an equidigital number, since it uses as much as digits as its factorization.

2157961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 126 counting only the distinct ones).

The product of its digits is 3780, while the sum is 31.

The cubic root of 2157961 is about 129.2253936674.

The spelling of 2157961 in words is "two million, one hundred fifty-seven thousand, nine hundred sixty-one".