21826979 has 2 divisors, whose sum is σ = 21826980. Its totient is φ = 21826978.

The previous prime is 21826969. The next prime is 21826993. The reversal of 21826979 is 97962812.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21826979 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21826969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10913489 + 10913490.

It is an arithmetic number, because the mean of its divisors is an integer number (10913490).

Almost surely, 2^21826979 is an apocalyptic number.

21826979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21826979 is an equidigital number, since it uses as much as digits as its factorization.

21826979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 44.

The square root of 21826979 is about 4671.9352521198. The cubic root of 21826979 is about 279.4674358265.

The spelling of 21826979 in words is "twenty-one million, eight hundred twenty-six thousand, nine hundred seventy-nine".