21346979 has 2 divisors, whose sum is σ = 21346980. Its totient is φ = 21346978.

The previous prime is 21346961. The next prime is 21346981. The reversal of 21346979 is 97964312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21346979 - 2¹² = 21342883 is a prime.

Together with 21346981, 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 (21346939) 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, 10673489 + 10673490.

It is an arithmetic number, because the mean of its divisors is an integer number (10673490).

Almost surely, 2^21346979 is an apocalyptic number.

21346979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21346979 is an equidigital number, since it uses as much as digits as its factorization.

21346979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 41.

The square root of 21346979 is about 4620.2791041235. The cubic root of 21346979 is about 277.4036307418.

The spelling of 21346979 in words is "twenty-one million, three hundred forty-six thousand, nine hundred seventy-nine".