1213221320 has 64 divisors (see below), whose sum is σ = 2907310320. Its totient is φ = 454057984.

The previous prime is 1213221313. The next prime is 1213221323. The reversal of 1213221320 is 231223121.

It can be written as a sum of positive squares in 8 ways, for example, as 920879716 + 292341604 = 30346^2 + 17098^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is not an unprimeable number, because it can be changed into a prime (1213221323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 112484 + ... + 122796.

Almost surely, 2^1213221320 is an apocalyptic number.

1213221320 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 1213221320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1453655160).

1213221320 is an abundant number, since it is smaller than the sum of its proper divisors (1694089000).

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

1213221320 is a wasteful number, since it uses less digits than its factorization.

1213221320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10514 (or 10510 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 1213221320 is about 34831.3267045629. The cubic root of 1213221320 is about 1066.5470312873.

Adding to 1213221320 its reverse (231223121), we get a palindrome (1444444441).

The spelling of 1213221320 in words is "one billion, two hundred thirteen million, two hundred twenty-one thousand, three hundred twenty".