131221311220 has 72 divisors (see below), whose sum is σ = 294347584440. Its totient is φ = 49127639040.

The previous prime is 131221311173. The next prime is 131221311253. The reversal of 131221311220 is 22113122131.

It can be written as a sum of positive squares in 12 ways, for example, as 49995171216 + 81226140004 = 223596^2 + 285002^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 983466 + ... + 1108894.

It is an arithmetic number, because the mean of its divisors is an integer number (4088160895).

Almost surely, 2^131221311220 is an apocalyptic number.

131221311220 is a gapful number since it is divisible by the number (10) 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 131221311220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147173792220).

131221311220 is an abundant number, since it is smaller than the sum of its proper divisors (163126273220).

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

131221311220 is a wasteful number, since it uses less digits than its factorization.

131221311220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125653 (or 125634 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

Adding to 131221311220 its reverse (22113122131), we get a palindrome (153334433351).

The spelling of 131221311220 in words is "one hundred thirty-one billion, two hundred twenty-one million, three hundred eleven thousand, two hundred twenty".