1321221312 has 168 divisors, whose sum is σ = 3902805504. Its totient is φ = 427155456.

The previous prime is 1321221289. The next prime is 1321221313. The reversal of 1321221312 is 2131221231.

1321221312 is a `hidden beast` number, since 132 + 1 + 221 + 312 = 666.

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 not an unprimeable number, because it can be changed into a prime (1321221313) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3449473 + ... + 3449855.

Almost surely, 2^1321221312 is an apocalyptic number.

1321221312 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 1321221312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1951402752).

1321221312 is an abundant number, since it is smaller than the sum of its proper divisors (2581584192).

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

1321221312 is a wasteful number, since it uses less digits than its factorization.

1321221312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567 (or 554 counting only the distinct ones).

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

The square root of 1321221312 is about 36348.6081164052. The cubic root of 1321221312 is about 1097.2995223640.

Adding to 1321221312 its reverse (2131221231), we get a palindrome (3452442543).

The spelling of 1321221312 in words is "one billion, three hundred twenty-one million, two hundred twenty-one thousand, three hundred twelve".