2561397 has 4 divisors (see below), whose sum is σ = 3415200. Its totient is φ = 1707596.

The previous prime is 2561389. The next prime is 2561401. The reversal of 2561397 is 7931652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2561397 - 2³ = 2561389 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 426897 + ... + 426902.

It is an arithmetic number, because the mean of its divisors is an integer number (853800).

2^2561397 is an apocalyptic number.

It is an amenable number.

2561397 is a deficient number, since it is larger than the sum of its proper divisors (853803).

2561397 is an equidigital number, since it uses as much as digits as its factorization.

2561397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853802.

The product of its digits is 11340, while the sum is 33.

The square root of 2561397 is about 1600.4365029579. The cubic root of 2561397 is about 136.8229549216.

It can be divided in two parts, 256 and 1397, that added together give a triangular number (1653 = T₅₇).

The spelling of 2561397 in words is "two million, five hundred sixty-one thousand, three hundred ninety-seven".