1221365888 has 24 divisors (see below), whose sum is σ = 2433977805. Its totient is φ = 610485248.

The previous prime is 1221365801. The next prime is 1221365909. The reversal of 1221365888 is 8885631221.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 944209984 + 277155904 = 30728^2 + 16648^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=24712.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 393848 + ... + 396936.

Almost surely, 2^1221365888 is an apocalyptic number.

It is an amenable number.

1221365888 is a deficient number, since it is larger than the sum of its proper divisors (1212611917).

1221365888 is an frugal number, since it uses more digits than its factorization.

1221365888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6192 (or 3091 counting only the distinct ones).

The product of its digits is 184320, while the sum is 44.

The square root of 1221365888 is about 34948.0455533639. The cubic root of 1221365888 is about 1068.9283497122.

The spelling of 1221365888 in words is "one billion, two hundred twenty-one million, three hundred sixty-five thousand, eight hundred eighty-eight".