25641821 has 2 divisors, whose sum is σ = 25641822. Its totient is φ = 25641820.

The previous prime is 25641793. The next prime is 25641823. The reversal of 25641821 is 12814652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13039321 + 12602500 = 3611^2 + 3550^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25641821 is a prime.

It is a Sophie Germain prime.

Together with 25641823, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25641823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12820910 + 12820911.

It is an arithmetic number, because the mean of its divisors is an integer number (12820911).

Almost surely, 2^25641821 is an apocalyptic number.

It is an amenable number.

25641821 is a deficient number, since it is larger than the sum of its proper divisors (1).

25641821 is an equidigital number, since it uses as much as digits as its factorization.

25641821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3840, while the sum is 29.

The square root of 25641821 is about 5063.7753702154. The cubic root of 25641821 is about 294.8829220365.

It can be divided in two parts, 25641 and 821, that added together give a palindrome (26462).

The spelling of 25641821 in words is "twenty-five million, six hundred forty-one thousand, eight hundred twenty-one".