21212012121 has 8 divisors (see below), whose sum is σ = 28283398080. Its totient is φ = 14140983792.

The previous prime is 21212012069. The next prime is 21212012141. The reversal of 21212012121 is 12121021212.

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

It is not a de Polignac number, because 21212012121 - 2¹⁵ = 21211979353 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212012121.

It is not an unprimeable number, because it can be changed into a prime (21212012141) 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, 117196 + ... + 236978.

It is an arithmetic number, because the mean of its divisors is an integer number (3535424760).

Almost surely, 2^21212012121 is an apocalyptic number.

It is an amenable number.

21212012121 is a deficient number, since it is larger than the sum of its proper divisors (7071385959).

21212012121 is a wasteful number, since it uses less digits than its factorization.

21212012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178815.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21212012121 its reverse (12121021212), we get a palindrome (33333033333).

Subtracting from 21212012121 its reverse (12121021212), we obtain a palindrome (9090990909).

The spelling of 21212012121 in words is "twenty-one billion, two hundred twelve million, twelve thousand, one hundred twenty-one".