81200173 has 2 divisors, whose sum is σ = 81200174. Its totient is φ = 81200172.

The previous prime is 81200137. The next prime is 81200183. The reversal of 81200173 is 37100218.

Together with previous prime (81200137) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44983849 + 36216324 = 6707^2 + 6018^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81200173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81200113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40600086 + 40600087.

It is an arithmetic number, because the mean of its divisors is an integer number (40600087).

Almost surely, 2^81200173 is an apocalyptic number.

It is an amenable number.

81200173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81200173 is an equidigital number, since it uses as much as digits as its factorization.

81200173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 81200173 is about 9011.1138601174. The cubic root of 81200173 is about 433.0309969329.

The spelling of 81200173 in words is "eighty-one million, two hundred thousand, one hundred seventy-three".