21902429 has 2 divisors, whose sum is σ = 21902430. Its totient is φ = 21902428.

The previous prime is 21902411. The next prime is 21902431. The reversal of 21902429 is 92420912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14212900 + 7689529 = 3770^2 + 2773^2 .

It is a cyclic number.

It is not a de Polignac number, because 21902429 - 2⁸ = 21902173 is a prime.

It is a super-2 number, since 2×21902429² = 959432792200082, which contains 22 as substring.

Together with 21902431, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21902479) 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, 10951214 + 10951215.

It is an arithmetic number, because the mean of its divisors is an integer number (10951215).

Almost surely, 2^21902429 is an apocalyptic number.

It is an amenable number.

21902429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21902429 is an equidigital number, since it uses as much as digits as its factorization.

21902429 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21902429 is about 4680.0030982896. The cubic root of 21902429 is about 279.7890801026.

Subtracting from 21902429 its sum of digits (29), we obtain a square (21902400 = 4680²).

The spelling of 21902429 in words is "twenty-one million, nine hundred two thousand, four hundred twenty-nine".