21112121311 has 4 divisors (see below), whose sum is σ = 21112412632. Its totient is φ = 21111829992.

The previous prime is 21112121269. The next prime is 21112121351. The reversal of 21112121311 is 11312121112.

It is a happy number.

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-21112121311 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 (21112121351) 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, 57481 + ... + 213373.

It is an arithmetic number, because the mean of its divisors is an integer number (5278103158).

Almost surely, 2^21112121311 is an apocalyptic number.

21112121311 is a deficient number, since it is larger than the sum of its proper divisors (291321).

21112121311 is a wasteful number, since it uses less digits than its factorization.

21112121311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291320.

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

Adding to 21112121311 its reverse (11312121112), we get a palindrome (32424242423).

The spelling of 21112121311 in words is "twenty-one billion, one hundred twelve million, one hundred twenty-one thousand, three hundred eleven".