81817147 has 2 divisors, whose sum is σ = 81817148. Its totient is φ = 81817146.

The previous prime is 81817121. The next prime is 81817163. The reversal of 81817147 is 74171818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81817147 - 2⁷ = 81817019 is a prime.

It is not a weakly prime, because it can be changed into another prime (81812147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40908573 + 40908574.

It is an arithmetic number, because the mean of its divisors is an integer number (40908574).

Almost surely, 2^81817147 is an apocalyptic number.

81817147 is a deficient number, since it is larger than the sum of its proper divisors (1).

81817147 is an equidigital number, since it uses as much as digits as its factorization.

81817147 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12544, while the sum is 37.

The square root of 81817147 is about 9045.2831354248. The cubic root of 81817147 is about 434.1249808174.

The spelling of 81817147 in words is "eighty-one million, eight hundred seventeen thousand, one hundred forty-seven".