1216090861 has 2 divisors, whose sum is σ = 1216090862. Its totient is φ = 1216090860.

The previous prime is 1216090853. The next prime is 1216090879. The reversal of 1216090861 is 1680906121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1077086761 + 139004100 = 32819^2 + 11790^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216090861 - 2³ = 1216090853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216094861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608045430 + 608045431.

It is an arithmetic number, because the mean of its divisors is an integer number (608045431).

Almost surely, 2^1216090861 is an apocalyptic number.

It is an amenable number.

1216090861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216090861 is an equidigital number, since it uses as much as digits as its factorization.

1216090861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 1216090861 is about 34872.4943329266. The cubic root of 1216090861 is about 1067.3872436558.

Adding to 1216090861 its reverse (1680906121), we get a palindrome (2896996982).

The spelling of 1216090861 in words is "one billion, two hundred sixteen million, ninety thousand, eight hundred sixty-one".