21112221312 has 384 divisors, whose sum is σ = 76807436160. Its totient is φ = 5416574976.

The previous prime is 21112221311. The next prime is 21112221323. The reversal of 21112221312 is 21312221112.

21112221312 is a `hidden beast` number, since 21 + 112 + 221 + 312 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

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

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is not an unprimeable number, because it can be changed into a prime (21112221311) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3876063 + ... + 3881505.

It is an arithmetic number, because the mean of its divisors is an integer number (200019365).

Almost surely, 2^21112221312 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 21112221312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38403718080).

21112221312 is an abundant number, since it is smaller than the sum of its proper divisors (55695214848).

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

21112221312 is a wasteful number, since it uses less digits than its factorization.

21112221312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5520 (or 5505 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

Adding to 21112221312 its reverse (21312221112), we get a palindrome (42424442424).

The spelling of 21112221312 in words is "twenty-one billion, one hundred twelve million, two hundred twenty-one thousand, three hundred twelve".