21937879 has 2 divisors, whose sum is σ = 21937880. Its totient is φ = 21937878.

The previous prime is 21937873. The next prime is 21937897. The reversal of 21937879 is 97873912.

It is a happy number.

Together with next prime (21937897) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21937879 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21937873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10968939 + 10968940.

It is an arithmetic number, because the mean of its divisors is an integer number (10968940).

Almost surely, 2^21937879 is an apocalyptic number.

21937879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21937879 is an equidigital number, since it uses as much as digits as its factorization.

21937879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 190512, while the sum is 46.

The square root of 21937879 is about 4683.7889576709. The cubic root of 21937879 is about 279.9399488565.

The spelling of 21937879 in words is "twenty-one million, nine hundred thirty-seven thousand, eight hundred seventy-nine".