25439681 has 2 divisors, whose sum is σ = 25439682. Its totient is φ = 25439680.

The previous prime is 25439677. The next prime is 25439717. The reversal of 25439681 is 18693452.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23961025 + 1478656 = 4895^2 + 1216^2 .

It is a cyclic number.

It is not a de Polignac number, because 25439681 - 2² = 25439677 is a prime.

It is a super-2 number, since 2×25439681² = 1294354738763522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (25439581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12719840 + 12719841.

It is an arithmetic number, because the mean of its divisors is an integer number (12719841).

Almost surely, 2^25439681 is an apocalyptic number.

It is an amenable number.

25439681 is a deficient number, since it is larger than the sum of its proper divisors (1).

25439681 is an equidigital number, since it uses as much as digits as its factorization.

25439681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 38.

The square root of 25439681 is about 5043.7764621363. The cubic root of 25439681 is about 294.1060016981.

The spelling of 25439681 in words is "twenty-five million, four hundred thirty-nine thousand, six hundred eighty-one".