25641221 has 2 divisors, whose sum is σ = 25641222. Its totient is φ = 25641220.

The previous prime is 25641211. The next prime is 25641227. The reversal of 25641221 is 12214652.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21520321 + 4120900 = 4639^2 + 2030^2 .

It is a cyclic number.

It is not a de Polignac number, because 25641221 - 2⁶ = 25641157 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25641227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12820610 + 12820611.

It is an arithmetic number, because the mean of its divisors is an integer number (12820611).

Almost surely, 2^25641221 is an apocalyptic number.

It is an amenable number.

25641221 is a deficient number, since it is larger than the sum of its proper divisors (1).

25641221 is an equidigital number, since it uses as much as digits as its factorization.

25641221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 23.

The square root of 25641221 is about 5063.7161255347. The cubic root of 25641221 is about 294.8806220031.

Adding to 25641221 its reverse (12214652), we get a palindrome (37855873).

It can be divided in two parts, 25641 and 221, that multiplied together give a triangular number (5666661 = T₃₃₆₆).

The spelling of 25641221 in words is "twenty-five million, six hundred forty-one thousand, two hundred twenty-one".