21239111 has 4 divisors (see below), whose sum is σ = 21254112. Its totient is φ = 21224112.

The previous prime is 21239087. The next prime is 21239173. The reversal of 21239111 is 11193212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21239111 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 (21239191) 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, 5126 + ... + 8291.

It is an arithmetic number, because the mean of its divisors is an integer number (5313528).

Almost surely, 2^21239111 is an apocalyptic number.

21239111 is a deficient number, since it is larger than the sum of its proper divisors (15001).

21239111 is a wasteful number, since it uses less digits than its factorization.

21239111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15000.

The product of its digits is 108, while the sum is 20.

The square root of 21239111 is about 4608.5909994270. The cubic root of 21239111 is about 276.9355939004.

The spelling of 21239111 in words is "twenty-one million, two hundred thirty-nine thousand, one hundred eleven".