21100222121 has 12 divisors (see below), whose sum is σ = 23348482500. Its totient is φ = 19053265440.

The previous prime is 21100222109. The next prime is 21100222123. The reversal of 21100222121 is 12122200112.

It can be written as a sum of positive squares in 2 ways, for example, as 2133423721 + 18966798400 = 46189^2 + 137720^2 .

It is not a de Polignac number, because 21100222121 - 2¹⁸ = 21099959977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100222096 and 21100222105.

It is not an unprimeable number, because it can be changed into a prime (21100222123) 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, 567146 + ... + 603203.

It is an arithmetic number, because the mean of its divisors is an integer number (1945706875).

Almost surely, 2^21100222121 is an apocalyptic number.

It is an amenable number.

21100222121 is a deficient number, since it is larger than the sum of its proper divisors (2248260379).

21100222121 is a wasteful number, since it uses less digits than its factorization.

21100222121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1170520 (or 1170509 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21100222121 its reverse (12122200112), we get a palindrome (33222422233).

The spelling of 21100222121 in words is "twenty-one billion, one hundred million, two hundred twenty-two thousand, one hundred twenty-one".