81693173 has 2 divisors, whose sum is σ = 81693174. Its totient is φ = 81693172.

The previous prime is 81693113. The next prime is 81693247. The reversal of 81693173 is 37139618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81306289 + 386884 = 9017^2 + 622^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81693173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81693113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40846586 + 40846587.

It is an arithmetic number, because the mean of its divisors is an integer number (40846587).

Almost surely, 2^81693173 is an apocalyptic number.

It is an amenable number.

81693173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81693173 is an equidigital number, since it uses as much as digits as its factorization.

81693173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 38.

The square root of 81693173 is about 9038.4275734223. The cubic root of 81693173 is about 433.9055996768.

The spelling of 81693173 in words is "eighty-one million, six hundred ninety-three thousand, one hundred seventy-three".