25603681 has 4 divisors (see below), whose sum is σ = 25615764. Its totient is φ = 25591600.

The previous prime is 25603679. The next prime is 25603691. The reversal of 25603681 is 18630652.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7617600 + 17986081 = 2760^2 + 4241^2 .

It is a cyclic number.

It is not a de Polignac number, because 25603681 - 2¹ = 25603679 is a prime.

It is a super-2 number, since 2×25603681² = 1311096961499522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25603631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1930 + ... + 7411.

It is an arithmetic number, because the mean of its divisors is an integer number (6403941).

Almost surely, 2^25603681 is an apocalyptic number.

It is an amenable number.

25603681 is a deficient number, since it is larger than the sum of its proper divisors (12083).

25603681 is an equidigital number, since it uses as much as digits as its factorization.

25603681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12082.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 25603681 is about 5060.0080039462. The cubic root of 25603681 is about 294.7366451725.

It can be divided in two parts, 256036 and 81, that multiplied together give a square (20738916 = 4554²).

The spelling of 25603681 in words is "twenty-five million, six hundred three thousand, six hundred eighty-one".