21121212111210 has 64 divisors (see below), whose sum is σ = 56485547337600. Its totient is φ = 5616091725696.

The previous prime is 21121212111163. The next prime is 21121212111217. The reversal of 21121212111210 is 1211121212112.

It is a happy number.

21121212111210 is a `hidden beast` number, since 211 + 2 + 121 + 211 + 121 + 0 = 666.

It is a super-2 number, since 2×21121212111210² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21121212111217) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 112624915 + ... + 112812294.

It is an arithmetic number, because the mean of its divisors is an integer number (882586677150).

Almost surely, 2^{21121212111210} is an apocalyptic number.

21121212111210 is an abundant number, since it is smaller than the sum of its proper divisors (35364335226390).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121212111210 is a wasteful number, since it uses less digits than its factorization.

21121212111210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225437572 (or 225437566 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21121212111210 its reverse (1211121212112), we get a palindrome (22332333323322).

The spelling of 21121212111210 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, one hundred eleven thousand, two hundred ten".