21326429 has 2 divisors, whose sum is σ = 21326430. Its totient is φ = 21326428.

The previous prime is 21326413. The next prime is 21326441. The reversal of 21326429 is 92462312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 487204 = 4565^2 + 698^2 .

It is a cyclic number.

It is not a de Polignac number, because 21326429 - 2⁴ = 21326413 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1349291 and since 21326429 and 1349291 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21326479) 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, 10663214 + 10663215.

It is an arithmetic number, because the mean of its divisors is an integer number (10663215).

Almost surely, 2^21326429 is an apocalyptic number.

It is an amenable number.

21326429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21326429 is an equidigital number, since it uses as much as digits as its factorization.

21326429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 29.

The square root of 21326429 is about 4618.0546770258. The cubic root of 21326429 is about 277.3145865284.

The spelling of 21326429 in words is "twenty-one million, three hundred twenty-six thousand, four hundred twenty-nine".