21921111 has 10 divisors (see below), whose sum is σ = 32746472. Its totient is φ = 14614020.

The previous prime is 21921083. The next prime is 21921113. The reversal of 21921111 is 11112912.

It is a happy number.

It is not a de Polignac number, because 21921111 - 2¹¹ = 21919063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921113) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 135235 + ... + 135396.

Almost surely, 2^21921111 is an apocalyptic number.

21921111 is a deficient number, since it is larger than the sum of its proper divisors (10825361).

21921111 is an equidigital number, since it uses as much as digits as its factorization.

21921111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270643 (or 270634 counting only the distinct ones).

The product of its digits is 36, while the sum is 18.

The square root of 21921111 is about 4681.9986117042. The cubic root of 21921111 is about 279.8686075703.

The spelling of 21921111 in words is "twenty-one million, nine hundred twenty-one thousand, one hundred eleven".