21425431 has 2 divisors, whose sum is σ = 21425432. Its totient is φ = 21425430.

The previous prime is 21425419. The next prime is 21425471. The reversal of 21425431 is 13452412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21425431 - 2⁵ = 21425399 is a prime.

It is a super-2 number, since 2×21425431² = 918098187071522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21425401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712715 + 10712716.

It is an arithmetic number, because the mean of its divisors is an integer number (10712716).

Almost surely, 2^21425431 is an apocalyptic number.

21425431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21425431 is an equidigital number, since it uses as much as digits as its factorization.

21425431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 22.

The square root of 21425431 is about 4628.7612813797. The cubic root of 21425431 is about 277.7430427619.

Adding to 21425431 its reverse (13452412), we get a palindrome (34877843).

The spelling of 21425431 in words is "twenty-one million, four hundred twenty-five thousand, four hundred thirty-one".