21124111 has 4 divisors (see below), whose sum is σ = 21141424. Its totient is φ = 21106800.

The previous prime is 21124099. The next prime is 21124123. The reversal of 21124111 is 11142112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21124099) and next prime (21124123).

It is a cyclic number.

It is not a de Polignac number, because 21124111 - 2⁵ = 21124079 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21124091 and 21124100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21124141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6675 + ... + 9316.

It is an arithmetic number, because the mean of its divisors is an integer number (5285356).

Almost surely, 2^21124111 is an apocalyptic number.

21124111 is a deficient number, since it is larger than the sum of its proper divisors (17313).

21124111 is a wasteful number, since it uses less digits than its factorization.

21124111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17312.

The product of its digits is 16, while the sum is 13.

The square root of 21124111 is about 4596.0973662445. The cubic root of 21124111 is about 276.4348628538.

Adding to 21124111 its reverse (11142112), we get a palindrome (32266223).

The spelling of 21124111 in words is "twenty-one million, one hundred twenty-four thousand, one hundred eleven".