25557661 has 2 divisors, whose sum is σ = 25557662. Its totient is φ = 25557660.

The previous prime is 25557659. The next prime is 25557667. The reversal of 25557661 is 16675552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14707225 + 10850436 = 3835^2 + 3294^2 .

It is a cyclic number.

It is not a de Polignac number, because 25557661 - 2¹ = 25557659 is a prime.

Together with 25557659, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 25557661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25557667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12778830 + 12778831.

It is an arithmetic number, because the mean of its divisors is an integer number (12778831).

Almost surely, 2^25557661 is an apocalyptic number.

It is an amenable number.

25557661 is a deficient number, since it is larger than the sum of its proper divisors (1).

25557661 is an equidigital number, since it uses as much as digits as its factorization.

25557661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63000, while the sum is 37.

The square root of 25557661 is about 5055.4585350886. The cubic root of 25557661 is about 294.5599529352.

The spelling of 25557661 in words is "twenty-five million, five hundred fifty-seven thousand, six hundred sixty-one".