21111120231 has 4 divisors (see below), whose sum is σ = 28148160312. Its totient is φ = 14074080152.

The previous prime is 21111120181. The next prime is 21111120241. The reversal of 21111120231 is 13202111112.

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 21111120231 - 2⁶ = 21111120167 is a prime.

It is a super-2 number, since 2×21111120231² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21111120231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111120241) 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, 3518520036 + ... + 3518520041.

It is an arithmetic number, because the mean of its divisors is an integer number (7037040078).

Almost surely, 2^21111120231 is an apocalyptic number.

21111120231 is a deficient number, since it is larger than the sum of its proper divisors (7037040081).

21111120231 is an equidigital number, since it uses as much as digits as its factorization.

21111120231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7037040080.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21111120231 its reverse (13202111112), we get a palindrome (34313231343).

The spelling of 21111120231 in words is "twenty-one billion, one hundred eleven million, one hundred twenty thousand, two hundred thirty-one".