21216223124220 has 96 divisors (see below), whose sum is σ = 59972811816960. Its totient is φ = 5603692272640.

The previous prime is 21216223124207. The next prime is 21216223124231. The reversal of 21216223124220 is 2242132261212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8669125 + ... + 10843715.

It is an arithmetic number, because the mean of its divisors is an integer number (624716789760).

Almost surely, 2^{21216223124220} is an apocalyptic number.

21216223124220 is a gapful number since it is divisible by the number (20) 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 21216223124220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29986405908480).

21216223124220 is an abundant number, since it is smaller than the sum of its proper divisors (38756588692740).

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

21216223124220 is a wasteful number, since it uses less digits than its factorization.

21216223124220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2176155 (or 2176153 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

Adding to 21216223124220 its reverse (2242132261212), we get a palindrome (23458355385432).

The spelling of 21216223124220 in words is "twenty-one trillion, two hundred sixteen billion, two hundred twenty-three million, one hundred twenty-four thousand, two hundred twenty".