1231816613 has 2 divisors, whose sum is σ = 1231816614. Its totient is φ = 1231816612.

The previous prime is 1231816601. The next prime is 1231816631. The reversal of 1231816613 is 3166181321.

1231816613 = 24817² + 24818².

Together with next prime (1231816631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 615933124 + 615883489 = 24818^2 + 24817^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231816613 - 2¹⁶ = 1231751077 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1231816613.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231816643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615908306 + 615908307.

It is an arithmetic number, because the mean of its divisors is an integer number (615908307).

Almost surely, 2^1231816613 is an apocalyptic number.

1231816613 is the 24818-th centered square number.

It is an amenable number.

1231816613 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231816613 is an equidigital number, since it uses as much as digits as its factorization.

1231816613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 1231816613 is about 35097.2450913174. The cubic root of 1231816613 is about 1071.9684883090.

Adding to 1231816613 its reverse (3166181321), we get a palindrome (4397997934).

The spelling of 1231816613 in words is "one billion, two hundred thirty-one million, eight hundred sixteen thousand, six hundred thirteen".