1681898081 has 2 divisors, whose sum is σ = 1681898082. Its totient is φ = 1681898080.

The previous prime is 1681898063. The next prime is 1681898147. The reversal of 1681898081 is 1808981861.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1681738081 + 160000 = 41009^2 + 400^2 .

It is an emirp because it is prime and its reverse (1808981861) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1808681891 and 1981868081.

It is a cyclic number.

It is not a de Polignac number, because 1681898081 - 2³⁰ = 608156257 is a prime.

It is a super-2 number, since 2×1681898081² = 5657562309742965122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1681898041) 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, 840949040 + 840949041.

It is an arithmetic number, because the mean of its divisors is an integer number (840949041).

Almost surely, 2^1681898081 is an apocalyptic number.

It is an amenable number.

1681898081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681898081 is an equidigital number, since it uses as much as digits as its factorization.

1681898081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 221184, while the sum is 50.

The square root of 1681898081 is about 41010.9507448925. The cubic root of 1681898081 is about 1189.2319222642.

The spelling of 1681898081 in words is "one billion, six hundred eighty-one million, eight hundred ninety-eight thousand, eighty-one".