21320111 has 4 divisors (see below), whose sum is σ = 21333000. Its totient is φ = 21307224.

The previous prime is 21320107. The next prime is 21320183. The reversal of 21320111 is 11102312.

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

It is a cyclic number.

It is not a de Polignac number, because 21320111 - 2² = 21320107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21320092 and 21320101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3521 + ... + 7418.

It is an arithmetic number, because the mean of its divisors is an integer number (5333250).

Almost surely, 2^21320111 is an apocalyptic number.

21320111 is a deficient number, since it is larger than the sum of its proper divisors (12889).

21320111 is a wasteful number, since it uses less digits than its factorization.

21320111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12888.

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

The square root of 21320111 is about 4617.3705720897. The cubic root of 21320111 is about 277.2871988114.

Adding to 21320111 its reverse (11102312), we get a palindrome (32422423).

The spelling of 21320111 in words is "twenty-one million, three hundred twenty thousand, one hundred eleven".