81678841 has 2 divisors, whose sum is σ = 81678842. Its totient is φ = 81678840.

The previous prime is 81678799. The next prime is 81678851. The reversal of 81678841 is 14887618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41229241 + 40449600 = 6421^2 + 6360^2 .

It is a cyclic number.

It is not a de Polignac number, because 81678841 - 2¹⁷ = 81547769 is a prime.

It is not a weakly prime, because it can be changed into another prime (81678851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40839420 + 40839421.

It is an arithmetic number, because the mean of its divisors is an integer number (40839421).

Almost surely, 2^81678841 is an apocalyptic number.

It is an amenable number.

81678841 is a deficient number, since it is larger than the sum of its proper divisors (1).

81678841 is an equidigital number, since it uses as much as digits as its factorization.

81678841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86016, while the sum is 43.

The square root of 81678841 is about 9037.6347016241. The cubic root of 81678841 is about 433.8802238364.

The spelling of 81678841 in words is "eighty-one million, six hundred seventy-eight thousand, eight hundred forty-one".