1216505749 has 2 divisors, whose sum is σ = 1216505750. Its totient is φ = 1216505748.

The previous prime is 1216505743. The next prime is 1216505777. The reversal of 1216505749 is 9475056121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 752404900 + 464100849 = 27430^2 + 21543^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216505749 - 2¹⁵ = 1216472981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216505743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608252874 + 608252875.

It is an arithmetic number, because the mean of its divisors is an integer number (608252875).

Almost surely, 2^1216505749 is an apocalyptic number.

It is an amenable number.

1216505749 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216505749 is an equidigital number, since it uses as much as digits as its factorization.

1216505749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 75600, while the sum is 40.

The square root of 1216505749 is about 34878.4424680919. The cubic root of 1216505749 is about 1067.5086150164.

The spelling of 1216505749 in words is "one billion, two hundred sixteen million, five hundred five thousand, seven hundred forty-nine".