21920911 has 2 divisors, whose sum is σ = 21920912. Its totient is φ = 21920910.

The previous prime is 21920903. The next prime is 21920917. The reversal of 21920911 is 11902912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21920911 - 2³ = 21920903 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21920917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10960455 + 10960456.

It is an arithmetic number, because the mean of its divisors is an integer number (10960456).

Almost surely, 2^21920911 is an apocalyptic number.

21920911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21920911 is an equidigital number, since it uses as much as digits as its factorization.

21920911 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 21920911 is about 4681.9772532553. The cubic root of 21920911 is about 279.8677564289.

The spelling of 21920911 in words is "twenty-one million, nine hundred twenty thousand, nine hundred eleven".