81185185 has 8 divisors (see below), whose sum is σ = 97485480. Its totient is φ = 64905984.

The previous prime is 81185179. The next prime is 81185191. The reversal of 81185185 is 58158118.

It is an interprime number because it is at equal distance from previous prime (81185179) and next prime (81185191).

It can be written as a sum of positive squares in 4 ways, for example, as 23104 + 81162081 = 152^2 + 9009^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81185185 - 2⁷ = 81185057 is a prime.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 5031 + ... + 13699.

It is an arithmetic number, because the mean of its divisors is an integer number (12185685).

Almost surely, 2^81185185 is an apocalyptic number.

It is an amenable number.

81185185 is a deficient number, since it is larger than the sum of its proper divisors (16300295).

81185185 is a wasteful number, since it uses less digits than its factorization.

81185185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10547.

The product of its digits is 12800, while the sum is 37.

The square root of 81185185 is about 9010.2821820407. The cubic root of 81185185 is about 433.0043522116.

The spelling of 81185185 in words is "eighty-one million, one hundred eighty-five thousand, one hundred eighty-five".