21031321111 has 4 divisors (see below), whose sum is σ = 21125632192. Its totient is φ = 20937010032.

The previous prime is 21031321093. The next prime is 21031321127. The reversal of 21031321111 is 11112313012.

It is a happy number.

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 21031321111 - 2⁷ = 21031320983 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 (21031321151) 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, 47155206 + ... + 47155651.

It is an arithmetic number, because the mean of its divisors is an integer number (5281408048).

Almost surely, 2^21031321111 is an apocalyptic number.

21031321111 is a deficient number, since it is larger than the sum of its proper divisors (94311081).

21031321111 is an equidigital number, since it uses as much as digits as its factorization.

21031321111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94311080.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21031321111 its reverse (11112313012), we get a palindrome (32143634123).

The spelling of 21031321111 in words is "twenty-one billion, thirty-one million, three hundred twenty-one thousand, one hundred eleven".