25635721 has 2 divisors, whose sum is σ = 25635722. Its totient is φ = 25635720.

The previous prime is 25635713. The next prime is 25635761. The reversal of 25635721 is 12753652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17015625 + 8620096 = 4125^2 + 2936^2 .

It is a cyclic number.

It is not a de Polignac number, because 25635721 - 2³ = 25635713 is a prime.

It is not a weakly prime, because it can be changed into another prime (25635761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12817860 + 12817861.

It is an arithmetic number, because the mean of its divisors is an integer number (12817861).

Almost surely, 2^25635721 is an apocalyptic number.

It is an amenable number.

25635721 is a deficient number, since it is larger than the sum of its proper divisors (1).

25635721 is an equidigital number, since it uses as much as digits as its factorization.

25635721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12600, while the sum is 31.

The square root of 25635721 is about 5063.1730169924. The cubic root of 25635721 is about 294.8595366917.

It can be divided in two parts, 256 and 35721, that multiplied together give a square (9144576 = 3024²).

The spelling of 25635721 in words is "twenty-five million, six hundred thirty-five thousand, seven hundred twenty-one".