1805340781 has 2 divisors, whose sum is σ = 1805340782. Its totient is φ = 1805340780.

The previous prime is 1805340773. The next prime is 1805340787. The reversal of 1805340781 is 1870435081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1041094756 + 764246025 = 32266^2 + 27645^2 .

It is a cyclic number.

It is not a de Polignac number, because 1805340781 - 2³ = 1805340773 is a prime.

It is a super-2 number, since 2×1805340781² = 6518510671083379922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1805340781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1805340787) 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, 902670390 + 902670391.

It is an arithmetic number, because the mean of its divisors is an integer number (902670391).

Almost surely, 2^1805340781 is an apocalyptic number.

It is an amenable number.

1805340781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1805340781 is an equidigital number, since it uses as much as digits as its factorization.

1805340781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 1805340781 is about 42489.3019594344. The cubic root of 1805340781 is about 1217.6423114937.

The spelling of 1805340781 in words is "one billion, eight hundred five million, three hundred forty thousand, seven hundred eighty-one".