1816985761 has 2 divisors, whose sum is σ = 1816985762. Its totient is φ = 1816985760.

The previous prime is 1816985759. The next prime is 1816985767. The reversal of 1816985761 is 1675896181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1807865361 + 9120400 = 42519^2 + 3020^2 .

It is an emirp because it is prime and its reverse (1675896181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1816985761 - 2¹ = 1816985759 is a prime.

Together with 1816985759, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1816985699 and 1816985708.

It is not a weakly prime, because it can be changed into another prime (1816985767) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 908492880 + 908492881.

It is an arithmetic number, because the mean of its divisors is an integer number (908492881).

Almost surely, 2^1816985761 is an apocalyptic number.

It is an amenable number.

1816985761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1816985761 is an equidigital number, since it uses as much as digits as its factorization.

1816985761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 52.

The square root of 1816985761 is about 42626.1159502012. The cubic root of 1816985761 is about 1220.2547530800.

The spelling of 1816985761 in words is "one billion, eight hundred sixteen million, nine hundred eighty-five thousand, seven hundred sixty-one".