21121220111212 has 48 divisors (see below), whose sum is σ = 42690969790560. Its totient is φ = 9060940482048.

The previous prime is 21121220111207. The next prime is 21121220111221. The reversal of 21121220111212 is 21211102212112.

It is a happy number.

It is a super-2 number, since 2×21121220111212² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a self number, because there is not a number n which added to its sum of digits gives 21121220111212.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 201624553 + ... + 201729280.

It is an arithmetic number, because the mean of its divisors is an integer number (889395203970).

Almost surely, 2^{21121220111212} is an apocalyptic number.

It is an amenable number.

21121220111212 is an abundant number, since it is smaller than the sum of its proper divisors (21569749679348).

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

21121220111212 is a wasteful number, since it uses less digits than its factorization.

21121220111212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403353922 (or 403353920 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21121220111212 its reverse (21211102212112), we get a palindrome (42332322323324).

The spelling of 21121220111212 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty million, one hundred eleven thousand, two hundred twelve".