81681169 has 8 divisors (see below), whose sum is σ = 82988928. Its totient is φ = 80377920.

The previous prime is 81681167. The next prime is 81681191. The reversal of 81681169 is 96118618.

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 81681169 - 2¹ = 81681167 is a prime.

It is a super-2 number, since 2×81681169² = 13343626738413122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81681167) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62329 + ... + 63625.

It is an arithmetic number, because the mean of its divisors is an integer number (10373616).

Almost surely, 2^81681169 is an apocalyptic number.

It is an amenable number.

81681169 is a deficient number, since it is larger than the sum of its proper divisors (1307759).

81681169 is a wasteful number, since it uses less digits than its factorization.

81681169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2255.

The product of its digits is 20736, while the sum is 40.

The square root of 81681169 is about 9037.7634954672. The cubic root of 81681169 is about 433.8843459304.

The spelling of 81681169 in words is "eighty-one million, six hundred eighty-one thousand, one hundred sixty-nine".