1221365889 has 6 divisors (see below), whose sum is σ = 1764195186. Its totient is φ = 814243920.

The previous prime is 1221365801. The next prime is 1221365909. The reversal of 1221365889 is 9885631221.

1221365889 is a `hidden beast` number, since 12 + 21 + 36 + 588 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1137038400 + 84327489 = 33720^2 + 9183^2 .

It is not a de Polignac number, because 1221365889 - 2⁸ = 1221365633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221345889) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 67853652 + ... + 67853669.

It is an arithmetic number, because the mean of its divisors is an integer number (294032531).

Almost surely, 2^1221365889 is an apocalyptic number.

It is an amenable number.

1221365889 is a deficient number, since it is larger than the sum of its proper divisors (542829297).

1221365889 is a wasteful number, since it uses less digits than its factorization.

1221365889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135707327 (or 135707324 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 1221365889 is about 34948.0455676709. The cubic root of 1221365889 is about 1068.9283500039.

The spelling of 1221365889 in words is "one billion, two hundred twenty-one million, three hundred sixty-five thousand, eight hundred eighty-nine".