25856981 has 2 divisors, whose sum is σ = 25856982. Its totient is φ = 25856980.

The previous prime is 25856977. The next prime is 25857031. The reversal of 25856981 is 18965852.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13140625 + 12716356 = 3625^2 + 3566^2 .

It is a cyclic number.

It is not a de Polignac number, because 25856981 - 2² = 25856977 is a prime.

It is a super-2 number, since 2×25856981² = 1337166932868722, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25856921) 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, 12928490 + 12928491.

It is an arithmetic number, because the mean of its divisors is an integer number (12928491).

Almost surely, 2^25856981 is an apocalyptic number.

It is an amenable number.

25856981 is a deficient number, since it is larger than the sum of its proper divisors (1).

25856981 is an equidigital number, since it uses as much as digits as its factorization.

25856981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172800, while the sum is 44.

The square root of 25856981 is about 5084.9760078097. The cubic root of 25856981 is about 295.7054113508.

The spelling of 25856981 in words is "twenty-five million, eight hundred fifty-six thousand, nine hundred eighty-one".