21221233212 has 96 divisors (see below), whose sum is σ = 53172770112. Its totient is φ = 6563823616.

The previous prime is 21221233183. The next prime is 21221233213. The reversal of 21221233212 is 21233212212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221233213) 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, 4538908 + ... + 4543580.

It is an arithmetic number, because the mean of its divisors is an integer number (553883022).

Almost surely, 2^21221233212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221233212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26586385056).

21221233212 is an abundant number, since it is smaller than the sum of its proper divisors (31951536900).

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

21221233212 is a wasteful number, since it uses less digits than its factorization.

21221233212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5007 (or 5005 counting only the distinct ones).

The product of its digits is 576, while the sum is 21.

Adding to 21221233212 its reverse (21233212212), we get a palindrome (42454445424).

The spelling of 21221233212 in words is "twenty-one billion, two hundred twenty-one million, two hundred thirty-three thousand, two hundred twelve".