1216306565 has 32 divisors (see below), whose sum is σ = 1635448320. Its totient is φ = 862977024.

The previous prime is 1216306547. The next prime is 1216306601. The reversal of 1216306565 is 5656036121.

It is a cyclic number.

It is not a de Polignac number, because 1216306565 - 2⁶ = 1216306501 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 316244 + ... + 320066.

It is an arithmetic number, because the mean of its divisors is an integer number (51107760).

Almost surely, 2^1216306565 is an apocalyptic number.

It is an amenable number.

1216306565 is a deficient number, since it is larger than the sum of its proper divisors (419141755).

1216306565 is a wasteful number, since it uses less digits than its factorization.

1216306565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4061.

The product of its (nonzero) digits is 32400, while the sum is 35.

The square root of 1216306565 is about 34875.5869484658. The cubic root of 1216306565 is about 1067.4503491616.

The spelling of 1216306565 in words is "one billion, two hundred sixteen million, three hundred six thousand, five hundred sixty-five".