1221313100220 has 144 divisors (see below), whose sum is σ = 3742156454400. Its totient is φ = 322388811648.

The previous prime is 1221313100153. The next prime is 1221313100221. The reversal of 1221313100220 is 220013131221.

1221313100220 is a `hidden beast` number, since 1 + 2 + 2 + 131 + 310 + 0 + 220 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 1221313100193 and 1221313100202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221313100221) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 50027257 + ... + 50051663.

It is an arithmetic number, because the mean of its divisors is an integer number (25987197600).

Almost surely, 2^{1221313100220} is an apocalyptic number.

1221313100220 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 1221313100220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1871078227200).

1221313100220 is an abundant number, since it is smaller than the sum of its proper divisors (2520843354180).

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

1221313100220 is a wasteful number, since it uses less digits than its factorization.

1221313100220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27224 (or 27219 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 1221313100220 its reverse (220013131221), we get a palindrome (1441326231441).

The spelling of 1221313100220 in words is "one trillion, two hundred twenty-one billion, three hundred thirteen million, one hundred thousand, two hundred twenty".