21231031212 has 72 divisors (see below), whose sum is σ = 55294759520. Its totient is φ = 6865585920.

The previous prime is 21231031193. The next prime is 21231031223. The reversal of 21231031212 is 21213013212.

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

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, 94089 + ... + 226527.

Almost surely, 2^21231031212 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 21231031212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27647379760).

21231031212 is an abundant number, since it is smaller than the sum of its proper divisors (34063728308).

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

21231031212 is a wasteful number, since it uses less digits than its factorization.

21231031212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132583 (or 132578 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21231031212 its reverse (21213013212), we get a palindrome (42444044424).

The spelling of 21231031212 in words is "twenty-one billion, two hundred thirty-one million, thirty-one thousand, two hundred twelve".