1216051765 has 4 divisors (see below), whose sum is σ = 1459262124. Its totient is φ = 972841408.

The previous prime is 1216051757. The next prime is 1216051799. The reversal of 1216051765 is 5671506121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 197739844 + 1018311921 = 14062^2 + 31911^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216051765 - 2³ = 1216051757 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1216051765.

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 3 ways as a sum of consecutive naturals, for example, 121605172 + ... + 121605181.

It is an arithmetic number, because the mean of its divisors is an integer number (364815531).

Almost surely, 2^1216051765 is an apocalyptic number.

It is an amenable number.

1216051765 is a deficient number, since it is larger than the sum of its proper divisors (243210359).

1216051765 is an equidigital number, since it uses as much as digits as its factorization.

1216051765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243210358.

The product of its (nonzero) digits is 12600, while the sum is 34.

The square root of 1216051765 is about 34871.9337720179. The cubic root of 1216051765 is about 1067.3758050865.

Adding to 1216051765 its reverse (5671506121), we get a palindrome (6887557886).

The spelling of 1216051765 in words is "one billion, two hundred sixteen million, fifty-one thousand, seven hundred sixty-five".