21019879 has 2 divisors, whose sum is σ = 21019880. Its totient is φ = 21019878.

The previous prime is 21019849. The next prime is 21019903. The reversal of 21019879 is 97891012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21019879 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21019849) 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, 10509939 + 10509940.

It is an arithmetic number, because the mean of its divisors is an integer number (10509940).

Almost surely, 2^21019879 is an apocalyptic number.

21019879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019879 is an equidigital number, since it uses as much as digits as its factorization.

21019879 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21019879 is about 4584.7441586200. The cubic root of 21019879 is about 275.9794451891.

The spelling of 21019879 in words is "twenty-one million, nineteen thousand, eight hundred seventy-nine".