21231121111 has 2 divisors, whose sum is σ = 21231121112. Its totient is φ = 21231121110.

The previous prime is 21231121103. The next prime is 21231121117. The reversal of 21231121111 is 11112113212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21231121111 - 2³ = 21231121103 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21231121117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615560555 + 10615560556.

It is an arithmetic number, because the mean of its divisors is an integer number (10615560556).

Almost surely, 2^21231121111 is an apocalyptic number.

21231121111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231121111 is an equidigital number, since it uses as much as digits as its factorization.

21231121111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24, while the sum is 16.

Adding to 21231121111 its reverse (11112113212), we get a palindrome (32343234323).

It can be divided in two parts, 21 and 231121111, that added together give a palindrome (231121132).

The spelling of 21231121111 in words is "twenty-one billion, two hundred thirty-one million, one hundred twenty-one thousand, one hundred eleven".