21211112121 has 8 divisors (see below), whose sum is σ = 28703594784. Its totient is φ = 13929685440.

The previous prime is 21211112017. The next prime is 21211112147. The reversal of 21211112121 is 12121111212.

It is a happy number.

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

It is not a de Polignac number, because 21211112121 - 2¹⁵ = 21211079353 is a prime.

It is a super-2 number, since 2×21211112121² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21211112121.

It is not an unprimeable number, because it can be changed into a prime (21211112191) 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, 52763760 + ... + 52764161.

It is an arithmetic number, because the mean of its divisors is an integer number (3587949348).

Almost surely, 2^21211112121 is an apocalyptic number.

It is an amenable number.

21211112121 is a deficient number, since it is larger than the sum of its proper divisors (7492482663).

21211112121 is a wasteful number, since it uses less digits than its factorization.

21211112121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105527991.

The product of its digits is 16, while the sum is 15.

Adding to 21211112121 its reverse (12121111212), we get a palindrome (33332223333).

Subtracting from 21211112121 its reverse (12121111212), we obtain a palindrome (9090000909).

The spelling of 21211112121 in words is "twenty-one billion, two hundred eleven million, one hundred twelve thousand, one hundred twenty-one".