1221131131220 has 288 divisors, whose sum is σ = 3473198550528. Its totient is φ = 350925696000.

The previous prime is 1221131131211. The next prime is 1221131131249. The reversal of 1221131131220 is 221311311221.

It is a super-2 number, since 2×1221131131220² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 1221131131192 and 1221131131201.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 224841905 + ... + 224847335.

Almost surely, 2^{1221131131220} is an apocalyptic number.

1221131131220 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 1221131131220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1736599275264).

1221131131220 is an abundant number, since it is smaller than the sum of its proper divisors (2252067419308).

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

1221131131220 is a wasteful number, since it uses less digits than its factorization.

1221131131220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6503 (or 6490 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

Adding to 1221131131220 its reverse (221311311221), we get a palindrome (1442442442441).

The spelling of 1221131131220 in words is "one trillion, two hundred twenty-one billion, one hundred thirty-one million, one hundred thirty-one thousand, two hundred twenty".