2561720297 has 4 divisors (see below), whose sum is σ = 2567277636. Its totient is φ = 2556162960.

The previous prime is 2561720251. The next prime is 2561720299. The reversal of 2561720297 is 7920271652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 565060441 + 1996659856 = 23771^2 + 44684^2 .

It is a cyclic number.

It is not a de Polignac number, because 2561720297 - 2⁸ = 2561720041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2561720299) 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, 2777978 + ... + 2778899.

It is an arithmetic number, because the mean of its divisors is an integer number (641819409).

Almost surely, 2^2561720297 is an apocalyptic number.

It is an amenable number.

2561720297 is a deficient number, since it is larger than the sum of its proper divisors (5557339).

2561720297 is an equidigital number, since it uses as much as digits as its factorization.

2561720297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5557338.

The product of its (nonzero) digits is 105840, while the sum is 41.

The square root of 2561720297 is about 50613.4398850740. The cubic root of 2561720297 is about 1368.2871123218.

The spelling of 2561720297 in words is "two billion, five hundred sixty-one million, seven hundred twenty thousand, two hundred ninety-seven".