25981 has 2 divisors, whose sum is σ = 25982. Its totient is φ = 25980.

The previous prime is 25969. The next prime is 25997. The reversal of 25981 is 18952.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22500 + 3481 = 150^2 + 59^2 .

It is a cyclic number.

It is not a de Polignac number, because 25981 - 2⁹ = 25469 is a prime.

It is a super-2 number, since 2×25981² = 1350024722, which contains 22 as substring.

It is a nialpdrome in base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12990 + 12991.

It is an arithmetic number, because the mean of its divisors is an integer number (12991).

2²⁵⁹⁸¹ is an apocalyptic number.

It is an amenable number.

25981 is a deficient number, since it is larger than the sum of its proper divisors (1).

25981 is an equidigital number, since it uses as much as digits as its factorization.

25981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720, while the sum is 25.

The square root of 25981 is about 161.1862276995. The cubic root of 25981 is about 29.6177425890.

The spelling of 25981 in words is "twenty-five thousand, nine hundred eighty-one".