25431221 has 2 divisors, whose sum is σ = 25431222. Its totient is φ = 25431220.

The previous prime is 25431209. The next prime is 25431223. The reversal of 25431221 is 12213452.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25300900 + 130321 = 5030^2 + 361^2 .

It is a cyclic number.

It is not a de Polignac number, because 25431221 - 2⁶ = 25431157 is a prime.

It is a Sophie Germain prime.

Together with 25431223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 25431193 and 25431202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25431223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12715610 + 12715611.

It is an arithmetic number, because the mean of its divisors is an integer number (12715611).

Almost surely, 2^25431221 is an apocalyptic number.

It is an amenable number.

25431221 is a deficient number, since it is larger than the sum of its proper divisors (1).

25431221 is an equidigital number, since it uses as much as digits as its factorization.

25431221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 20.

The square root of 25431221 is about 5042.9377350905. The cubic root of 25431221 is about 294.0733963019.

Adding to 25431221 its reverse (12213452), we get a palindrome (37644673).

It can be divided in two parts, 25431 and 221, that added together give a palindrome (25652).

The spelling of 25431221 in words is "twenty-five million, four hundred thirty-one thousand, two hundred twenty-one".