21001122111 has 16 divisors (see below), whose sum is σ = 28604399616. Its totient is φ = 13700677536.

The previous prime is 21001122073. The next prime is 21001122173. The reversal of 21001122111 is 11122110012.

It is not a de Polignac number, because 21001122111 - 2¹⁰ = 21001121087 is a prime.

It is a super-2 number, since 2×21001122111² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001122011) 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, 111535 + ... + 233328.

It is an arithmetic number, because the mean of its divisors is an integer number (1787774976).

Almost surely, 2^21001122111 is an apocalyptic number.

21001122111 is a deficient number, since it is larger than the sum of its proper divisors (7603277505).

21001122111 is a wasteful number, since it uses less digits than its factorization.

21001122111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345302.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21001122111 its reverse (11122110012), we get a palindrome (32123232123).

It can be divided in two parts, 2100 and 1122111, that added together give a palindrome (1124211).

The spelling of 21001122111 in words is "twenty-one billion, one million, one hundred twenty-two thousand, one hundred eleven".