21432979 has 2 divisors, whose sum is σ = 21432980. Its totient is φ = 21432978.

The previous prime is 21432977. The next prime is 21432991. The reversal of 21432979 is 97923412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21432979 - 2¹ = 21432977 is a prime.

Together with 21432977, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21432973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716489 + 10716490.

It is an arithmetic number, because the mean of its divisors is an integer number (10716490).

Almost surely, 2^21432979 is an apocalyptic number.

21432979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21432979 is an equidigital number, since it uses as much as digits as its factorization.

21432979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 37.

The square root of 21432979 is about 4629.5765465105. The cubic root of 21432979 is about 277.7756544490.

The spelling of 21432979 in words is "twenty-one million, four hundred thirty-two thousand, nine hundred seventy-nine".