25561621 has 2 divisors, whose sum is σ = 25561622. Its totient is φ = 25561620.

The previous prime is 25561609. The next prime is 25561643. The reversal of 25561621 is 12616552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23174596 + 2387025 = 4814^2 + 1545^2 .

It is a cyclic number.

It is not a de Polignac number, because 25561621 - 2⁷ = 25561493 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 25561621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25561661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12780810 + 12780811.

It is an arithmetic number, because the mean of its divisors is an integer number (12780811).

Almost surely, 2^25561621 is an apocalyptic number.

It is an amenable number.

25561621 is a deficient number, since it is larger than the sum of its proper divisors (1).

25561621 is an equidigital number, since it uses as much as digits as its factorization.

25561621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 28.

The square root of 25561621 is about 5055.8501757865. The cubic root of 25561621 is about 294.5751655580.

The spelling of 25561621 in words is "twenty-five million, five hundred sixty-one thousand, six hundred twenty-one".