21011122111 has 8 divisors (see below), whose sum is σ = 24042846240. Its totient is φ = 17986931808.

The previous prime is 21011122091. The next prime is 21011122141. The reversal of 21011122111 is 11122111012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21011122111 - 2¹⁵ = 21011089343 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21011122091 and 21011122100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011122141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1877476 + ... + 1888633.

It is an arithmetic number, because the mean of its divisors is an integer number (3005355780).

Almost surely, 2^21011122111 is an apocalyptic number.

21011122111 is a deficient number, since it is larger than the sum of its proper divisors (3031724129).

21011122111 is an equidigital number, since it uses as much as digits as its factorization.

21011122111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3766913.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21011122111 its reverse (11122111012), we get a palindrome (32133233123).

The spelling of 21011122111 in words is "twenty-one billion, eleven million, one hundred twenty-two thousand, one hundred eleven".