21108911 has 2 divisors, whose sum is σ = 21108912. Its totient is φ = 21108910.

The previous prime is 21108889. The next prime is 21108929. The reversal of 21108911 is 11980112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21108911 - 2⁶ = 21108847 is a prime.

It is a super-2 number, since 2×21108911² = 891172247211842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21108811) 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, 10554455 + 10554456.

It is an arithmetic number, because the mean of its divisors is an integer number (10554456).

Almost surely, 2^21108911 is an apocalyptic number.

21108911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21108911 is an equidigital number, since it uses as much as digits as its factorization.

21108911 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 21108911 is about 4594.4434918715. The cubic root of 21108911 is about 276.3685434059.

The spelling of 21108911 in words is "twenty-one million, one hundred eight thousand, nine hundred eleven".