25819681 has 2 divisors, whose sum is σ = 25819682. Its totient is φ = 25819680.

The previous prime is 25819679. The next prime is 25819687. The reversal of 25819681 is 18691852.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15840400 + 9979281 = 3980^2 + 3159^2 .

It is a cyclic number.

It is not a de Polignac number, because 25819681 - 2¹ = 25819679 is a prime.

It is a super-2 number, since 2×25819681² = 1333311853883522, which contains 22 as substring.

Together with 25819679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (25819687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12909840 + 12909841.

It is an arithmetic number, because the mean of its divisors is an integer number (12909841).

Almost surely, 2^25819681 is an apocalyptic number.

It is an amenable number.

25819681 is a deficient number, since it is larger than the sum of its proper divisors (1).

25819681 is an equidigital number, since it uses as much as digits as its factorization.

25819681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 40.

The square root of 25819681 is about 5081.3070169003. The cubic root of 25819681 is about 295.5631529308.

The spelling of 25819681 in words is "twenty-five million, eight hundred nineteen thousand, six hundred eighty-one".