1221313440 has 48 divisors (see below), whose sum is σ = 3847138848. Its totient is φ = 325683456.

The previous prime is 1221313421. The next prime is 1221313441. The reversal of 1221313440 is 443131221.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (1221313441) 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 7 ways as a sum of consecutive naturals, for example, 1271722 + ... + 1272681.

It is an arithmetic number, because the mean of its divisors is an integer number (80148726).

Almost surely, 2^1221313440 is an apocalyptic number.

1221313440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221313440 is an abundant number, since it is smaller than the sum of its proper divisors (2625825408).

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

1221313440 is a wasteful number, since it uses less digits than its factorization.

1221313440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2544421 (or 2544413 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 1221313440 is about 34947.2951743050. The cubic root of 1221313440 is about 1068.9130488218.

Adding to 1221313440 its reverse (443131221), we get a palindrome (1664444661).

The spelling of 1221313440 in words is "one billion, two hundred twenty-one million, three hundred thirteen thousand, four hundred forty".