25857509 has 2 divisors, whose sum is σ = 25857510. Its totient is φ = 25857508.

The previous prime is 25857431. The next prime is 25857523. The reversal of 25857509 is 90575852.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23980609 + 1876900 = 4897^2 + 1370^2 .

It is a cyclic number.

It is not a de Polignac number, because 25857509 - 2²⁴ = 9080293 is a prime.

It is a super-2 number, since 2×25857509² = 1337221543370162, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25857529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12928754 + 12928755.

It is an arithmetic number, because the mean of its divisors is an integer number (12928755).

Almost surely, 2^25857509 is an apocalyptic number.

It is an amenable number.

25857509 is a deficient number, since it is larger than the sum of its proper divisors (1).

25857509 is an equidigital number, since it uses as much as digits as its factorization.

25857509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 126000, while the sum is 41.

The square root of 25857509 is about 5085.0279251937. The cubic root of 25857509 is about 295.7074241070.

The spelling of 25857509 in words is "twenty-five million, eight hundred fifty-seven thousand, five hundred nine".