21000111121 has 16 divisors (see below), whose sum is σ = 23209804800. Its totient is φ = 18841005520.

The previous prime is 21000111113. The next prime is 21000111149. The reversal of 21000111121 is 12111100012.

It is a cyclic number.

It is not a de Polignac number, because 21000111121 - 2³ = 21000111113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000111098 and 21000111107.

It is not an unprimeable number, because it can be changed into a prime (21000111161) 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, 885780 + ... + 909178.

It is an arithmetic number, because the mean of its divisors is an integer number (1450612800).

Almost surely, 2^21000111121 is an apocalyptic number.

It is an amenable number.

21000111121 is a deficient number, since it is larger than the sum of its proper divisors (2209693679).

21000111121 is a wasteful number, since it uses less digits than its factorization.

21000111121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24476.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21000111121 its reverse (12111100012), we get a palindrome (33111211133).

It can be divided in two parts, 210001 and 11121, that added together give a palindrome (221122).

The spelling of 21000111121 in words is "twenty-one billion, one hundred eleven thousand, one hundred twenty-one".