25401991 has 2 divisors, whose sum is σ = 25401992. Its totient is φ = 25401990.

The previous prime is 25401983. The next prime is 25402007. The reversal of 25401991 is 19910452.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 25401991 - 2³ = 25401983 is a prime.

It is a super-2 number, since 2×25401991² = 1290522293528162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25401091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12700995 + 12700996.

It is an arithmetic number, because the mean of its divisors is an integer number (12700996).

Almost surely, 2^25401991 is an apocalyptic number.

25401991 is a deficient number, since it is larger than the sum of its proper divisors (1).

25401991 is an equidigital number, since it uses as much as digits as its factorization.

25401991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 25401991 is about 5040.0387895333. The cubic root of 25401991 is about 293.9606862760.

The spelling of 25401991 in words is "twenty-five million, four hundred one thousand, nine hundred ninety-one".