81185205 has 32 divisors (see below), whose sum is σ = 133741440. Its totient is φ = 42036480.

The previous prime is 81185201. The next prime is 81185227. The reversal of 81185205 is 50258118.

It is not a de Polignac number, because 81185205 - 2² = 81185201 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81185201) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75411 + ... + 76479.

It is an arithmetic number, because the mean of its divisors is an integer number (4179420).

Almost surely, 2^81185205 is an apocalyptic number.

It is an amenable number.

81185205 is a deficient number, since it is larger than the sum of its proper divisors (52556235).

81185205 is a wasteful number, since it uses less digits than its factorization.

81185205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1221.

The product of its (nonzero) digits is 3200, while the sum is 30.

The square root of 81185205 is about 9010.2832918838. The cubic root of 81185205 is about 433.0043877685.

The spelling of 81185205 in words is "eighty-one million, one hundred eighty-five thousand, two hundred five".