21023111 has 2 divisors, whose sum is σ = 21023112. Its totient is φ = 21023110.

The previous prime is 21023099. The next prime is 21023113. The reversal of 21023111 is 11132012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21023111 - 2⁶ = 21023047 is a prime.

It is a super-2 number, since 2×21023111² = 883942392236642, which contains 22 as substring.

Together with 21023113, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21023092 and 21023101.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21023113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511555 + 10511556.

It is an arithmetic number, because the mean of its divisors is an integer number (10511556).

Almost surely, 2^21023111 is an apocalyptic number.

21023111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21023111 is an equidigital number, since it uses as much as digits as its factorization.

21023111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21023111 is about 4585.0966183931. The cubic root of 21023111 is about 275.9935892581.

Adding to 21023111 its reverse (11132012), we get a palindrome (32155123).

The spelling of 21023111 in words is "twenty-one million, twenty-three thousand, one hundred eleven".