21021323112 has 72 divisors (see below), whose sum is σ = 57504030870. Its totient is φ = 6937488000.

The previous prime is 21021323111. The next prime is 21021323117. The reversal of 21021323112 is 21132312012.

21021323112 is a `hidden beast` number, since 210 + 21 + 323 + 112 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 20530877796 + 490445316 = 143286^2 + 22146^2 .

It is a tau number, because it is divible by the number of its divisors (72).

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

It is not an unprimeable number, because it can be changed into a prime (21021323111) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 720162 + ... + 748782.

Almost surely, 2^21021323112 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 21021323112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28752015435).

21021323112 is an abundant number, since it is smaller than the sum of its proper divisors (36482707758).

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

21021323112 is a wasteful number, since it uses less digits than its factorization.

21021323112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28835 (or 28727 counting only the distinct ones).

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

Adding to 21021323112 its reverse (21132312012), we get a palindrome (42153635124).

The spelling of 21021323112 in words is "twenty-one billion, twenty-one million, three hundred twenty-three thousand, one hundred twelve".