81366165 has 96 divisors (see below), whose sum is σ = 159584256. Its totient is φ = 38154240.

The previous prime is 81366161. The next prime is 81366169. The reversal of 81366165 is 56166318.

81366165 = T₃₅₁ + T₃₅₂ + ... + T₈₀₉.

It is a happy number.

81366165 is a `hidden beast` number, since 8 + 1 + 36 + 616 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (81366161) and next prime (81366169).

It is not a de Polignac number, because 81366165 - 2² = 81366161 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81366161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1114569 + ... + 1114641.

It is an arithmetic number, because the mean of its divisors is an integer number (1662336).

Almost surely, 2^81366165 is an apocalyptic number.

81366165 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81366165 is a deficient number, since it is larger than the sum of its proper divisors (78218091).

81366165 is a wasteful number, since it uses less digits than its factorization.

81366165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179 (or 176 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 81366165 is about 9020.3195619667. The cubic root of 81366165 is about 433.3258680502.

The spelling of 81366165 in words is "eighty-one million, three hundred sixty-six thousand, one hundred sixty-five".