1213331220 has 72 divisors (see below), whose sum is σ = 3689660520. Its totient is φ = 322744320.

The previous prime is 1213331159. The next prime is 1213331237. The reversal of 1213331220 is 221333121.

It can be written as a sum of positive squares in 4 ways, for example, as 294877584 + 918453636 = 17172^2 + 30306^2 .

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 = 1213331193 and 1213331202.

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, 65380 + ... + 81860.

It is an arithmetic number, because the mean of its divisors is an integer number (51245285).

Almost surely, 2^1213331220 is an apocalyptic number.

1213331220 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 1213331220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1844830260).

1213331220 is an abundant number, since it is smaller than the sum of its proper divisors (2476329300).

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

1213331220 is a wasteful number, since it uses less digits than its factorization.

1213331220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16905 (or 16900 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 1213331220 is about 34832.9042716797. The cubic root of 1213331220 is about 1066.5792348041.

Adding to 1213331220 its reverse (221333121), we get a palindrome (1434664341).

The spelling of 1213331220 in words is "one billion, two hundred thirteen million, three hundred thirty-one thousand, two hundred twenty".