2561857 has 2 divisors, whose sum is σ = 2561858. Its totient is φ = 2561856.

The previous prime is 2561833. The next prime is 2561863. The reversal of 2561857 is 7581652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2547216 + 14641 = 1596^2 + 121^2 .

It is a cyclic number.

It is not a de Polignac number, because 2561857 - 2⁷ = 2561729 is a prime.

It is a super-2 number, since 2×2561857² = 13126222576898, which contains 22 as substring.

2561857 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (2561807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1280928 + 1280929.

It is an arithmetic number, because the mean of its divisors is an integer number (1280929).

2^2561857 is an apocalyptic number.

It is an amenable number.

2561857 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561857 is an equidigital number, since it uses as much as digits as its factorization.

2561857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16800, while the sum is 34.

The square root of 2561857 is about 1600.5802072998. The cubic root of 2561857 is about 136.8311450866.

The spelling of 2561857 in words is "two million, five hundred sixty-one thousand, eight hundred fifty-seven".