81678673 has 2 divisors, whose sum is σ = 81678674. Its totient is φ = 81678672.

The previous prime is 81678643. The next prime is 81678679. The reversal of 81678673 is 37687618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81504784 + 173889 = 9028^2 + 417^2 .

It is a cyclic number.

It is not a de Polignac number, because 81678673 - 2¹³ = 81670481 is a prime.

It is not a weakly prime, because it can be changed into another prime (81678679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40839336 + 40839337.

It is an arithmetic number, because the mean of its divisors is an integer number (40839337).

Almost surely, 2^81678673 is an apocalyptic number.

It is an amenable number.

81678673 is a deficient number, since it is larger than the sum of its proper divisors (1).

81678673 is an equidigital number, since it uses as much as digits as its factorization.

81678673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 46.

The square root of 81678673 is about 9037.6254071520. The cubic root of 81678673 is about 433.8799263627.

The spelling of 81678673 in words is "eighty-one million, six hundred seventy-eight thousand, six hundred seventy-three".