25804021 has 2 divisors, whose sum is σ = 25804022. Its totient is φ = 25804020.

The previous prime is 25804019. The next prime is 25804039. The reversal of 25804021 is 12040852.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25100100 + 703921 = 5010^2 + 839^2 .

It is a cyclic number.

It is not a de Polignac number, because 25804021 - 2¹ = 25804019 is a prime.

Together with 25804019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 25803983 and 25804001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25804001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12902010 + 12902011.

It is an arithmetic number, because the mean of its divisors is an integer number (12902011).

Almost surely, 2^25804021 is an apocalyptic number.

It is an amenable number.

25804021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25804021 is an equidigital number, since it uses as much as digits as its factorization.

25804021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 25804021 is about 5079.7658410600. The cubic root of 25804021 is about 295.5033864418.

Adding to 25804021 its reverse (12040852), we get a palindrome (37844873).

The spelling of 25804021 in words is "twenty-five million, eight hundred four thousand, twenty-one".