81682181 has 4 divisors (see below), whose sum is σ = 93351072. Its totient is φ = 70013292.

The previous prime is 81682147. The next prime is 81682187. The reversal of 81682181 is 18128618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81682181 - 2¹⁴ = 81665797 is a prime.

It is a super-2 number, since 2×81682181² = 13343957385833522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81682187) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5834435 + ... + 5834448.

It is an arithmetic number, because the mean of its divisors is an integer number (23337768).

Almost surely, 2^81682181 is an apocalyptic number.

It is an amenable number.

81682181 is a deficient number, since it is larger than the sum of its proper divisors (11668891).

81682181 is a wasteful number, since it uses less digits than its factorization.

81682181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11668890.

The product of its digits is 6144, while the sum is 35.

The square root of 81682181 is about 9037.8194825965. The cubic root of 81682181 is about 433.8861378127.

The spelling of 81682181 in words is "eighty-one million, six hundred eighty-two thousand, one hundred eighty-one".