21864111 has 16 divisors (see below), whose sum is σ = 30088800. Its totient is φ = 14113280.

The previous prime is 21864107. The next prime is 21864113. The reversal of 21864111 is 11146812.

It is not a de Polignac number, because 21864111 - 2² = 21864107 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864113) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17731 + ... + 18923.

It is an arithmetic number, because the mean of its divisors is an integer number (1880550).

Almost surely, 2^21864111 is an apocalyptic number.

21864111 is a deficient number, since it is larger than the sum of its proper divisors (8224689).

21864111 is a wasteful number, since it uses less digits than its factorization.

21864111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1386.

The product of its digits is 384, while the sum is 24.

The square root of 21864111 is about 4675.9075055009. The cubic root of 21864111 is about 279.6258224701.

The spelling of 21864111 in words is "twenty-one million, eight hundred sixty-four thousand, one hundred eleven".