1805212081 has 2 divisors, whose sum is σ = 1805212082. Its totient is φ = 1805212080.

The previous prime is 1805212067. The next prime is 1805212139. The reversal of 1805212081 is 1802125081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1708995600 + 96216481 = 41340^2 + 9809^2 .

It is a cyclic number.

It is not a de Polignac number, because 1805212081 - 2⁷ = 1805211953 is a prime.

It is a super-2 number, since 2×1805212081² = 6517581314776701122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1805212681) 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, 902606040 + 902606041.

It is an arithmetic number, because the mean of its divisors is an integer number (902606041).

Almost surely, 2^1805212081 is an apocalyptic number.

It is an amenable number.

1805212081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1805212081 is an equidigital number, since it uses as much as digits as its factorization.

1805212081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1280, while the sum is 28.

The square root of 1805212081 is about 42487.7874335673. The cubic root of 1805212081 is about 1217.6133761829.

The spelling of 1805212081 in words is "one billion, eight hundred five million, two hundred twelve thousand, eighty-one".