21929911 has 2 divisors, whose sum is σ = 21929912. Its totient is φ = 21929910.

The previous prime is 21929909. The next prime is 21929959. The reversal of 21929911 is 11992912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21929911 - 2¹ = 21929909 is a prime.

Together with 21929909, it forms a pair of twin primes.

It is equal to p_1385098 and since 21929911 and 1385098 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21920911) 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, 10964955 + 10964956.

It is an arithmetic number, because the mean of its divisors is an integer number (10964956).

Almost surely, 2^21929911 is an apocalyptic number.

21929911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21929911 is an equidigital number, since it uses as much as digits as its factorization.

21929911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2916, while the sum is 34.

The square root of 21929911 is about 4682.9382870160. The cubic root of 21929911 is about 279.9060526654.

The spelling of 21929911 in words is "twenty-one million, nine hundred twenty-nine thousand, nine hundred eleven".