21131321312220 has 192 divisors, whose sum is σ = 67720703533056. Its totient is φ = 4822844279040.

The previous prime is 21131321312207. The next prime is 21131321312239. The reversal of 21131321312220 is 2221312313112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 978880267 + ... + 978901853.

It is an arithmetic number, because the mean of its divisors is an integer number (352711997568).

Almost surely, 2^{21131321312220} is an apocalyptic number.

21131321312220 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 21131321312220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33860351766528).

21131321312220 is an abundant number, since it is smaller than the sum of its proper divisors (46589382220836).

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

21131321312220 is a wasteful number, since it uses less digits than its factorization.

21131321312220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24960 (or 24958 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

Adding to 21131321312220 its reverse (2221312313112), we get a palindrome (23352633625332).

The spelling of 21131321312220 in words is "twenty-one trillion, one hundred thirty-one billion, three hundred twenty-one million, three hundred twelve thousand, two hundred twenty".