21111311231 has 16 divisors (see below), whose sum is σ = 22458098880. Its totient is φ = 19800718080.

The previous prime is 21111311227. The next prime is 21111311239. The reversal of 21111311231 is 13211311112.

It is a cyclic number.

It is not a de Polignac number, because 21111311231 - 2² = 21111311227 is a prime.

It is a super-2 number, since 2×21111311231² (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 (21111311239) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2605835 + ... + 2613923.

It is an arithmetic number, because the mean of its divisors is an integer number (1403631180).

Almost surely, 2^21111311231 is an apocalyptic number.

21111311231 is a deficient number, since it is larger than the sum of its proper divisors (1346787649).

21111311231 is a wasteful number, since it uses less digits than its factorization.

21111311231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10306.

The product of its digits is 36, while the sum is 17.

Adding to 21111311231 its reverse (13211311112), we get a palindrome (34322622343).

The spelling of 21111311231 in words is "twenty-one billion, one hundred eleven million, three hundred eleven thousand, two hundred thirty-one".