21231321121220 has 144 divisors (see below), whose sum is σ = 52753077780480. Its totient is φ = 7155731310336.

The previous prime is 21231321121147. The next prime is 21231321121237. The reversal of 21231321121220 is 2212112313212.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12783629 + ... + 14348651.

It is an arithmetic number, because the mean of its divisors is an integer number (366340817920).

Almost surely, 2^{21231321121220} is an apocalyptic number.

21231321121220 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 21231321121220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26376538890240).

21231321121220 is an abundant number, since it is smaller than the sum of its proper divisors (31521756659260).

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

21231321121220 is a wasteful number, since it uses less digits than its factorization.

21231321121220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1565282 (or 1565273 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 21231321121220 its reverse (2212112313212), we get a palindrome (23443433434432).

The spelling of 21231321121220 in words is "twenty-one trillion, two hundred thirty-one billion, three hundred twenty-one million, one hundred twenty-one thousand, two hundred twenty".