1321221220 has 48 divisors (see below), whose sum is σ = 3078129600. Its totient is φ = 472296320.

The previous prime is 1321221217. The next prime is 1321221229. The reversal of 1321221220 is 221221231.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1321221194 and 1321221203.

It is not an unprimeable number, because it can be changed into a prime (1321221229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37915 + ... + 63874.

It is an arithmetic number, because the mean of its divisors is an integer number (64127700).

Almost surely, 2^1321221220 is an apocalyptic number.

1321221220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1321221220 is an abundant number, since it is smaller than the sum of its proper divisors (1756908380).

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

1321221220 is a wasteful number, since it uses less digits than its factorization.

1321221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101868 (or 101866 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 1321221220 is about 36348.6068508822. The cubic root of 1321221220 is about 1097.2994968947.

Adding to 1321221220 its reverse (221221231), we get a palindrome (1542442451).

The spelling of 1321221220 in words is "one billion, three hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty".