21121222212 has 72 divisors (see below), whose sum is σ = 57090203352. Its totient is φ = 6560640000.

The previous prime is 21121222211. The next prime is 21121222217. The reversal of 21121222212 is 21222212112.

It is a happy number.

21121222212 is a `hidden beast` number, since 211 + 21 + 222 + 212 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 10335568896 + 10785653316 = 101664^2 + 103854^2 .

It is a super-2 number, since 2×21121222212² (a number of 21 digits) contains 22 as substring.

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

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21121222211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 109039 + ... + 232662.

It is an arithmetic number, because the mean of its divisors is an integer number (792919491).

Almost surely, 2^21121222212 is an apocalyptic number.

It is an amenable number.

21121222212 is an abundant number, since it is smaller than the sum of its proper divisors (35968981140).

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

21121222212 is a wasteful number, since it uses less digits than its factorization.

21121222212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341829 (or 341824 counting only the distinct ones).

The product of its digits is 128, while the sum is 18.

Adding to 21121222212 its reverse (21222212112), we get a palindrome (42343434324).

The spelling of 21121222212 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twelve".