21042911 has 2 divisors, whose sum is σ = 21042912. Its totient is φ = 21042910.

The previous prime is 21042883. The next prime is 21042913. The reversal of 21042911 is 11924012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042911 is a prime.

Together with 21042913, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21042913) 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, 10521455 + 10521456.

It is an arithmetic number, because the mean of its divisors is an integer number (10521456).

Almost surely, 2^21042911 is an apocalyptic number.

21042911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042911 is an equidigital number, since it uses as much as digits as its factorization.

21042911 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 20.

The square root of 21042911 is about 4587.2552795762. The cubic root of 21042911 is about 276.0802075577.

Adding to 21042911 its reverse (11924012), we get a palindrome (32966923).

The spelling of 21042911 in words is "twenty-one million, forty-two thousand, nine hundred eleven".