1216581273 has 6 divisors (see below), whose sum is σ = 1757284074. Its totient is φ = 811054176.

The previous prime is 1216581271. The next prime is 1216581293. The reversal of 1216581273 is 3721856121.

1216581273 is a `hidden beast` number, since 1 + 2 + 1 + 6 + 581 + 2 + 73 = 666.

It can be written as a sum of positive squares in only one way, i.e., 773562969 + 443018304 = 27813^2 + 21048^2 .

It is not a de Polignac number, because 1216581273 - 2¹ = 1216581271 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216581271) 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 in 5 ways as a sum of consecutive naturals, for example, 67587840 + ... + 67587857.

It is an arithmetic number, because the mean of its divisors is an integer number (292880679).

Almost surely, 2^1216581273 is an apocalyptic number.

It is an amenable number.

1216581273 is a deficient number, since it is larger than the sum of its proper divisors (540702801).

1216581273 is a wasteful number, since it uses less digits than its factorization.

1216581273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135175703 (or 135175700 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 1216581273 is about 34879.5251257812. The cubic root of 1216581273 is about 1067.5307058429.

The spelling of 1216581273 in words is "one billion, two hundred sixteen million, five hundred eighty-one thousand, two hundred seventy-three".