1216231613 has 2 divisors, whose sum is σ = 1216231614. Its totient is φ = 1216231612.

The previous prime is 1216231589. The next prime is 1216231631. The reversal of 1216231613 is 3161326121.

Together with next prime (1216231631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1142237209 + 73994404 = 33797^2 + 8602^2 .

It is an emirp because it is prime and its reverse (3161326121) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216231613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216231213) by changing a digit.

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 as a sum of consecutive naturals, namely, 608115806 + 608115807.

It is an arithmetic number, because the mean of its divisors is an integer number (608115807).

Almost surely, 2^1216231613 is an apocalyptic number.

It is an amenable number.

1216231613 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216231613 is an equidigital number, since it uses as much as digits as its factorization.

1216231613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 26.

The square root of 1216231613 is about 34874.5123693508. The cubic root of 1216231613 is about 1067.4284223480.

Adding to 1216231613 its reverse (3161326121), we get a palindrome (4377557734).

The spelling of 1216231613 in words is "one billion, two hundred sixteen million, two hundred thirty-one thousand, six hundred thirteen".