21243421212 has 96 divisors (see below), whose sum is σ = 55167006720. Its totient is φ = 6318224640.

The previous prime is 21243421201. The next prime is 21243421217. The reversal of 21243421212 is 21212434212.

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 (21243421217) 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, 5283739 + ... + 5287757.

It is an arithmetic number, because the mean of its divisors is an integer number (574656320).

Almost surely, 2^21243421212 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 21243421212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27583503360).

21243421212 is an abundant number, since it is smaller than the sum of its proper divisors (33923585508).

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

21243421212 is a wasteful number, since it uses less digits than its factorization.

21243421212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5163 (or 5161 counting only the distinct ones).

The product of its digits is 1536, while the sum is 24.

Adding to 21243421212 its reverse (21212434212), we get a palindrome (42455855424).

The spelling of 21243421212 in words is "twenty-one billion, two hundred forty-three million, four hundred twenty-one thousand, two hundred twelve".