81969 has 8 divisors (see below), whose sum is σ = 110880. Its totient is φ = 53856.

The previous prime is 81967. The next prime is 81971. The reversal of 81969 is 96918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81967) and next prime (81971).

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

It is not a de Polignac number, because 81969 - 2¹ = 81967 is a prime.

It is a super-2 number, since 2×81969² = 13437833922, which contains 22 as substring.

81969 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (81967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 114 + ... + 420.

It is an arithmetic number, because the mean of its divisors is an integer number (13860).

2⁸¹⁹⁶⁹ is an apocalyptic number.

81969 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

81969 is a deficient number, since it is larger than the sum of its proper divisors (28911).

81969 is a wasteful number, since it uses less digits than its factorization.

81969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399.

The product of its digits is 3888, while the sum is 33.

The square root of 81969 is about 286.3022878008. The cubic root of 81969 is about 43.4393394145.

It can be divided in two parts, 819 and 69, that added together give a palindrome (888).

The spelling of 81969 in words is "eighty-one thousand, nine hundred sixty-nine".