25215991 has 2 divisors, whose sum is σ = 25215992. Its totient is φ = 25215990.

The previous prime is 25215979. The next prime is 25216001. The reversal of 25215991 is 19951252.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 25215991 - 2²³ = 16827383 is a prime.

It is a super-2 number, since 2×25215991² = 1271692404224162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25215901) 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, 12607995 + 12607996.

It is an arithmetic number, because the mean of its divisors is an integer number (12607996).

Almost surely, 2^25215991 is an apocalyptic number.

25215991 is a deficient number, since it is larger than the sum of its proper divisors (1).

25215991 is an equidigital number, since it uses as much as digits as its factorization.

25215991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8100, while the sum is 34.

The square root of 25215991 is about 5021.5526483350. The cubic root of 25215991 is about 293.2414423199.

The spelling of 25215991 in words is "twenty-five million, two hundred fifteen thousand, nine hundred ninety-one".