21111023231 has 4 divisors (see below), whose sum is σ = 21111314112. Its totient is φ = 21110732352.

The previous prime is 21111023221. The next prime is 21111023239. The reversal of 21111023231 is 13232011112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111023231 is a prime.

It is a super-2 number, since 2×21111023231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111023239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63026 + ... + 214928.

It is an arithmetic number, because the mean of its divisors is an integer number (5277828528).

Almost surely, 2^21111023231 is an apocalyptic number.

21111023231 is a deficient number, since it is larger than the sum of its proper divisors (290881).

21111023231 is a wasteful number, since it uses less digits than its factorization.

21111023231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290880.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21111023231 its reverse (13232011112), we get a palindrome (34343034343).

The spelling of 21111023231 in words is "twenty-one billion, one hundred eleven million, twenty-three thousand, two hundred thirty-one".