21312313121220 has 192 divisors, whose sum is σ = 66385256749056. Its totient is φ = 5065567211520.

The previous prime is 21312313121173. The next prime is 21312313121387. The reversal of 21312313121220 is 2212131321312.

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, 5294529 + ... + 8405751.

It is an arithmetic number, because the mean of its divisors is an integer number (345756545568).

Almost surely, 2^{21312313121220} is an apocalyptic number.

21312313121220 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 21312313121220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33192628374528).

21312313121220 is an abundant number, since it is smaller than the sum of its proper divisors (45072943627836).

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

21312313121220 is a wasteful number, since it uses less digits than its factorization.

21312313121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3111450 (or 3111448 counting only the distinct ones).

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

Adding to 21312313121220 its reverse (2212131321312), we get a palindrome (23524444442532).

The spelling of 21312313121220 in words is "twenty-one trillion, three hundred twelve billion, three hundred thirteen million, one hundred twenty-one thousand, two hundred twenty".