81747173 has 2 divisors, whose sum is σ = 81747174. Its totient is φ = 81747172.

The previous prime is 81747163. The next prime is 81747179. The reversal of 81747173 is 37174718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55100929 + 26646244 = 7423^2 + 5162^2 .

It is a cyclic number.

It is not a de Polignac number, because 81747173 - 2⁴ = 81747157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81747179) 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, 40873586 + 40873587.

It is an arithmetic number, because the mean of its divisors is an integer number (40873587).

Almost surely, 2^81747173 is an apocalyptic number.

It is an amenable number.

81747173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81747173 is an equidigital number, since it uses as much as digits as its factorization.

81747173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32928, while the sum is 38.

The square root of 81747173 is about 9041.4143252038. The cubic root of 81747173 is about 434.0011839251.

The spelling of 81747173 in words is "eighty-one million, seven hundred forty-seven thousand, one hundred seventy-three".