1221665368 has 96 divisors (see below), whose sum is σ = 2977178400. Its totient is φ = 459486720.

The previous prime is 1221665299. The next prime is 1221665369. The reversal of 1221665368 is 8635661221.

It is a self number, because there is not a number n which added to its sum of digits gives 1221665368.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221665369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 193396 + ... + 199612.

It is an arithmetic number, because the mean of its divisors is an integer number (31012275).

Almost surely, 2^1221665368 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221665368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1488589200).

1221665368 is an abundant number, since it is smaller than the sum of its proper divisors (1755513032).

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

1221665368 is a wasteful number, since it uses less digits than its factorization.

1221665368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6281 (or 6266 counting only the distinct ones).

The product of its digits is 103680, while the sum is 40.

The square root of 1221665368 is about 34952.3299366437. The cubic root of 1221665368 is about 1069.0157099657.

The spelling of 1221665368 in words is "one billion, two hundred twenty-one million, six hundred sixty-five thousand, three hundred sixty-eight".