81810185 has 8 divisors (see below), whose sum is σ = 98307456. Its totient is φ = 65358000.

The previous prime is 81810173. The next prime is 81810193. The reversal of 81810185 is 58101818.

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

It is not a de Polignac number, because 81810185 - 2¹² = 81806089 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7139 + ... + 14648.

It is an arithmetic number, because the mean of its divisors is an integer number (12288432).

Almost surely, 2^81810185 is an apocalyptic number.

It is an amenable number.

81810185 is a deficient number, since it is larger than the sum of its proper divisors (16497271).

81810185 is a wasteful number, since it uses less digits than its factorization.

81810185 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22543.

The product of its (nonzero) digits is 2560, while the sum is 32.

The square root of 81810185 is about 9044.8982857741. The cubic root of 81810185 is about 434.1126669201.

The spelling of 81810185 in words is "eighty-one million, eight hundred ten thousand, one hundred eighty-five".