1221365887 has 8 divisors (see below), whose sum is σ = 1398029472. Its totient is φ = 1045248000.

The previous prime is 1221365801. The next prime is 1221365909. The reversal of 1221365887 is 7885631221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221365887 - 2¹¹ = 1221363839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221362887) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131614 + ... + 140587.

It is an arithmetic number, because the mean of its divisors is an integer number (174753684).

Almost surely, 2^1221365887 is an apocalyptic number.

1221365887 is a deficient number, since it is larger than the sum of its proper divisors (176663585).

1221365887 is an equidigital number, since it uses as much as digits as its factorization.

1221365887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272849.

The product of its digits is 161280, while the sum is 43.

The square root of 1221365887 is about 34948.0455390570. The cubic root of 1221365887 is about 1068.9283494205.

The spelling of 1221365887 in words is "one billion, two hundred twenty-one million, three hundred sixty-five thousand, eight hundred eighty-seven".