21321231012 has 72 divisors (see below), whose sum is σ = 56306105856. Its totient is φ = 6789915264.

The previous prime is 21321230999. The next prime is 21321231031. The reversal of 21321231012 is 21013212312.

21321231012 is a `hidden beast` number, since 21 + 321 + 2 + 310 + 12 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 694573 + ... + 724619.

It is an arithmetic number, because the mean of its divisors is an integer number (782029248).

Almost surely, 2^21321231012 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 21321231012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28153052928).

21321231012 is an abundant number, since it is smaller than the sum of its proper divisors (34984874844).

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

21321231012 is a wasteful number, since it uses less digits than its factorization.

21321231012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30937 (or 30932 counting only the distinct ones).

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

Adding to 21321231012 its reverse (21013212312), we get a palindrome (42334443324).

The spelling of 21321231012 in words is "twenty-one billion, three hundred twenty-one million, two hundred thirty-one thousand, twelve".