25011991 has 2 divisors, whose sum is σ = 25011992. Its totient is φ = 25011990.

The previous prime is 25011911. The next prime is 25011997. The reversal of 25011991 is 19911052.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 25011991 - 2⁷ = 25011863 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25011997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12505995 + 12505996.

It is an arithmetic number, because the mean of its divisors is an integer number (12505996).

Almost surely, 2^25011991 is an apocalyptic number.

25011991 is a deficient number, since it is larger than the sum of its proper divisors (1).

25011991 is an equidigital number, since it uses as much as digits as its factorization.

25011991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 25011991 is about 5001.1989562504. The cubic root of 25011991 is about 292.4485155446.

The spelling of 25011991 in words is "twenty-five million, eleven thousand, nine hundred ninety-one".