21179959 has 2 divisors, whose sum is σ = 21179960. Its totient is φ = 21179958.

The previous prime is 21179911. The next prime is 21179989. The reversal of 21179959 is 95997112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21179959 - 2¹³ = 21171767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21179989) 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, 10589979 + 10589980.

It is an arithmetic number, because the mean of its divisors is an integer number (10589980).

Almost surely, 2^21179959 is an apocalyptic number.

21179959 is a deficient number, since it is larger than the sum of its proper divisors (1).

21179959 is an equidigital number, since it uses as much as digits as its factorization.

21179959 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51030, while the sum is 43.

The square root of 21179959 is about 4602.1689451823. The cubic root of 21179959 is about 276.6782616389.

The spelling of 21179959 in words is "twenty-one million, one hundred seventy-nine thousand, nine hundred fifty-nine".