81802381 has 2 divisors, whose sum is σ = 81802382. Its totient is φ = 81802380.

The previous prime is 81802363. The next prime is 81802411. The reversal of 81802381 is 18320818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81613156 + 189225 = 9034^2 + 435^2 .

It is a cyclic number.

It is not a de Polignac number, because 81802381 - 2⁵ = 81802349 is a prime.

It is a super-2 number, since 2×81802381² = 13383259074538322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81802321) 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, 40901190 + 40901191.

It is an arithmetic number, because the mean of its divisors is an integer number (40901191).

Almost surely, 2^81802381 is an apocalyptic number.

It is an amenable number.

81802381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81802381 is an equidigital number, since it uses as much as digits as its factorization.

81802381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 81802381 is about 9044.4668720716. The cubic root of 81802381 is about 434.0988629217.

The spelling of 81802381 in words is "eighty-one million, eight hundred two thousand, three hundred eighty-one".