1816205681 has 2 divisors, whose sum is σ = 1816205682. Its totient is φ = 1816205680.

The previous prime is 1816205669. The next prime is 1816205689. The reversal of 1816205681 is 1865026181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1139737600 + 676468081 = 33760^2 + 26009^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1816205681 is a prime.

It is a super-3 number, since 3×1816205681³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (1816205689) 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 as a sum of consecutive naturals, namely, 908102840 + 908102841.

It is an arithmetic number, because the mean of its divisors is an integer number (908102841).

Almost surely, 2^1816205681 is an apocalyptic number.

It is an amenable number.

1816205681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1816205681 is an equidigital number, since it uses as much as digits as its factorization.

1816205681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 38.

The square root of 1816205681 is about 42616.9647089044. The cubic root of 1816205681 is about 1220.0800988797.

The spelling of 1816205681 in words is "one billion, eight hundred sixteen million, two hundred five thousand, six hundred eighty-one".