21231023212 has 72 divisors (see below), whose sum is σ = 43590143520. Its totient is φ = 9021519360.

The previous prime is 21231023201. The next prime is 21231023237. The reversal of 21231023212 is 21232013212.

It is a self number, because there is not a number n which added to its sum of digits gives 21231023212.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12422214 + ... + 12423922.

It is an arithmetic number, because the mean of its divisors is an integer number (605418660).

Almost surely, 2^21231023212 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 21231023212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21795071760).

21231023212 is an abundant number, since it is smaller than the sum of its proper divisors (22359120308).

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

21231023212 is a wasteful number, since it uses less digits than its factorization.

21231023212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2231 (or 2222 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21231023212 its reverse (21232013212), we get a palindrome (42463036424).

The spelling of 21231023212 in words is "twenty-one billion, two hundred thirty-one million, twenty-three thousand, two hundred twelve".