81938173 has 2 divisors, whose sum is σ = 81938174. Its totient is φ = 81938172.

The previous prime is 81938141. The next prime is 81938179. The reversal of 81938173 is 37183918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80964004 + 974169 = 8998^2 + 987^2 .

It is a cyclic number.

It is not a de Polignac number, because 81938173 - 2⁵ = 81938141 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81938179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40969086 + 40969087.

It is an arithmetic number, because the mean of its divisors is an integer number (40969087).

Almost surely, 2^81938173 is an apocalyptic number.

It is an amenable number.

81938173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81938173 is an equidigital number, since it uses as much as digits as its factorization.

81938173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 40.

The square root of 81938173 is about 9051.9706694178. The cubic root of 81938173 is about 434.3389315875.

The spelling of 81938173 in words is "eighty-one million, nine hundred thirty-eight thousand, one hundred seventy-three".