1221221320 has 64 divisors (see below), whose sum is σ = 3100939200. Its totient is φ = 428762880.

The previous prime is 1221221279. The next prime is 1221221327. The reversal of 1221221320 is 231221221.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1221221294 and 1221221303.

It is not an unprimeable number, because it can be changed into a prime (1221221327) 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, 35094 + ... + 60613.

It is an arithmetic number, because the mean of its divisors is an integer number (48452175).

Almost surely, 2^1221221320 is an apocalyptic number.

1221221320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221221320 is an abundant number, since it is smaller than the sum of its proper divisors (1879717880).

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

1221221320 is a wasteful number, since it uses less digits than its factorization.

1221221320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95758 (or 95754 counting only the distinct ones).

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

The square root of 1221221320 is about 34945.9771647610. The cubic root of 1221221320 is about 1068.8861731805.

Adding to 1221221320 its reverse (231221221), we get a palindrome (1452442541).

Subtracting from 1221221320 its reverse (231221221), we obtain a palindrome (990000099).

The spelling of 1221221320 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, three hundred twenty".