21102111121 has 12 divisors (see below), whose sum is σ = 26435612532. Its totient is φ = 16696175328.

The previous prime is 21102111119. The next prime is 21102111137. The reversal of 21102111121 is 12111120112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2736440721 + 18365670400 = 52311^2 + 135520^2 .

It is not a de Polignac number, because 21102111121 - 2¹ = 21102111119 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is not an unprimeable number, because it can be changed into a prime (21102171121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16563030 + ... + 16564303.

It is an arithmetic number, because the mean of its divisors is an integer number (2202967711).

Almost surely, 2^21102111121 is an apocalyptic number.

It is an amenable number.

21102111121 is a deficient number, since it is larger than the sum of its proper divisors (5333501411).

21102111121 is a wasteful number, since it uses less digits than its factorization.

21102111121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33127360 (or 33127353 counting only the distinct ones).

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

Adding to 21102111121 its reverse (12111120112), we get a palindrome (33213231233).

The spelling of 21102111121 in words is "twenty-one billion, one hundred two million, one hundred eleven thousand, one hundred twenty-one".