21321011111 has 4 divisors (see below), whose sum is σ = 21321981912. Its totient is φ = 21320040312.

The previous prime is 21321011053. The next prime is 21321011119. The reversal of 21321011111 is 11111012312.

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-21321011111 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 (21321011119) 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, 451676 + ... + 496641.

It is an arithmetic number, because the mean of its divisors is an integer number (5330495478).

Almost surely, 2^21321011111 is an apocalyptic number.

21321011111 is a deficient number, since it is larger than the sum of its proper divisors (970801).

21321011111 is an equidigital number, since it uses as much as digits as its factorization.

21321011111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 970800.

The product of its (nonzero) digits is 12, while the sum is 14.

Adding to 21321011111 its reverse (11111012312), we get a palindrome (32432023423).

The spelling of 21321011111 in words is "twenty-one billion, three hundred twenty-one million, eleven thousand, one hundred eleven".