21221312112 has 960 divisors, whose sum is σ = 85950498816. Its totient is φ = 4707901440.

The previous prime is 21221312087. The next prime is 21221312153. The reversal of 21221312112 is 21121312212.

21221312112 is a `hidden beast` number, since 21 + 221 + 312 + 112 = 666.

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.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 122666458 + ... + 122666630.

Almost surely, 2^21221312112 is an apocalyptic number.

21221312112 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221312112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42975249408).

21221312112 is an abundant number, since it is smaller than the sum of its proper divisors (64729186704).

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

21221312112 is a wasteful number, since it uses less digits than its factorization.

21221312112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278 (or 269 counting only the distinct ones).

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

Adding to 21221312112 its reverse (21121312212), we get a palindrome (42342624324).

It can be divided in two parts, 21221 and 312112, that added together give a palindrome (333333).

The spelling of 21221312112 in words is "twenty-one billion, two hundred twenty-one million, three hundred twelve thousand, one hundred twelve".