81646841 has 2 divisors, whose sum is σ = 81646842. Its totient is φ = 81646840.

The previous prime is 81646813. The next prime is 81646883. The reversal of 81646841 is 14864618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74995600 + 6651241 = 8660^2 + 2579^2 .

It is a cyclic number.

It is not a de Polignac number, because 81646841 - 2¹⁸ = 81384697 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81646795 and 81646804.

It is not a weakly prime, because it can be changed into another prime (81696841) 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, 40823420 + 40823421.

It is an arithmetic number, because the mean of its divisors is an integer number (40823421).

Almost surely, 2^81646841 is an apocalyptic number.

It is an amenable number.

81646841 is a deficient number, since it is larger than the sum of its proper divisors (1).

81646841 is an equidigital number, since it uses as much as digits as its factorization.

81646841 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36864, while the sum is 38.

The square root of 81646841 is about 9035.8641534720. The cubic root of 81646841 is about 433.8235548119.

The spelling of 81646841 in words is "eighty-one million, six hundred forty-six thousand, eight hundred forty-one".