1221231312 has 180 divisors, whose sum is σ = 4210032996. Its totient is φ = 328366080.

The previous prime is 1221231307. The next prime is 1221231317. The reversal of 1221231312 is 2131321221.

1221231312 is a `hidden beast` number, since 122 + 1 + 231 + 312 = 666.

It is an interprime number because it is at equal distance from previous prime (1221231307) and next prime (1221231317).

It can be written as a sum of positive squares in 2 ways, for example, as 844716096 + 376515216 = 29064^2 + 19404^2 .

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

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221231317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 114862 + ... + 125042.

Almost surely, 2^1221231312 is an apocalyptic number.

1221231312 is a gapful number since it is divisible by the number (12) 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 1221231312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2105016498).

1221231312 is an abundant number, since it is smaller than the sum of its proper divisors (2988801684).

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

1221231312 is a wasteful number, since it uses less digits than its factorization.

1221231312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10226 (or 10210 counting only the distinct ones).

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

The square root of 1221231312 is about 34946.1201279913. The cubic root of 1221231312 is about 1068.8890883719.

Adding to 1221231312 its reverse (2131321221), we get a palindrome (3352552533).

The spelling of 1221231312 in words is "one billion, two hundred twenty-one million, two hundred thirty-one thousand, three hundred twelve".