21179911 has 2 divisors, whose sum is σ = 21179912. Its totient is φ = 21179910.

The previous prime is 21179891. The next prime is 21179959. The reversal of 21179911 is 11997112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21179911 - 2¹⁹ = 20655623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21179111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10589955 + 10589956.

It is an arithmetic number, because the mean of its divisors is an integer number (10589956).

Almost surely, 2^21179911 is an apocalyptic number.

21179911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21179911 is an equidigital number, since it uses as much as digits as its factorization.

21179911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1134, while the sum is 31.

The square root of 21179911 is about 4602.1637302469. The cubic root of 21179911 is about 276.6780526273.

The spelling of 21179911 in words is "twenty-one million, one hundred seventy-nine thousand, nine hundred eleven".