21211212222 has 144 divisors (see below), whose sum is σ = 50487554832. Its totient is φ = 6429818880.

The previous prime is 21211212173. The next prime is 21211212233. The reversal of 21211212222 is 22221211212.

It is a happy number.

21211212222 is a `hidden beast` number, since 21 + 211 + 212 + 222 = 666.

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 a junction number, because it is equal to n+sod(n) for n = 21211212195 and 21211212204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 37147197 + ... + 37147767.

Almost surely, 2^21211212222 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211212222, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25243777416).

21211212222 is an abundant number, since it is smaller than the sum of its proper divisors (29276342610).

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

21211212222 is a wasteful number, since it uses less digits than its factorization.

21211212222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843 (or 823 counting only the distinct ones).

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

Adding to 21211212222 its reverse (22221211212), we get a palindrome (43432423434).

The spelling of 21211212222 in words is "twenty-one billion, two hundred eleven million, two hundred twelve thousand, two hundred twenty-two".