1331221320 has 384 divisors, whose sum is σ = 5354294400. Its totient is φ = 282009600.

The previous prime is 1331221291. The next prime is 1331221321. The reversal of 1331221320 is 231221331.

1331221320 is a `hidden beast` number, since 13 + 312 + 21 + 320 = 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 = 1331221293 and 1331221302.

It is not an unprimeable number, because it can be changed into a prime (1331221321) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 977440 + ... + 978800.

It is an arithmetic number, because the mean of its divisors is an integer number (13943475).

Almost surely, 2^1331221320 is an apocalyptic number.

1331221320 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 1331221320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2677147200).

1331221320 is an abundant number, since it is smaller than the sum of its proper divisors (4023073080).

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

1331221320 is a wasteful number, since it uses less digits than its factorization.

1331221320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1421 (or 1414 counting only the distinct ones).

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

The square root of 1331221320 is about 36485.9057719553. The cubic root of 1331221320 is about 1100.0609663179.

Adding to 1331221320 its reverse (231221331), we get a palindrome (1562442651).

The spelling of 1331221320 in words is "one billion, three hundred thirty-one million, two hundred twenty-one thousand, three hundred twenty".