81389 has 12 divisors (see below), whose sum is σ = 103968. Its totient is φ = 63000.
The previous prime is 81373. The next prime is 81401. The reversal of 81389 is 98318.
It is a happy number.
It is not a de Polignac number, because 81389 - 24 = 81373 is a prime.
It is a Duffinian number.
It is a Curzon number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (81349) by changing a digit.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 464 + ... + 614.
It is an arithmetic number, because the mean of its divisors is an integer number (8664).
281389 is an apocalyptic number.
It is an amenable number.
81389 is a deficient number, since it is larger than the sum of its proper divisors (22579).
81389 is a wasteful number, since it uses less digits than its factorization.
81389 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 176 (or 169 counting only the distinct ones).
The product of its digits is 1728, while the sum is 29.
The square root of 81389 is about 285.2875742124. The cubic root of 81389 is about 43.3366401158.
Adding to 81389 its sum of digits (29), we get a palindrome (81418).
The spelling of 81389 in words is "eighty-one thousand, three hundred eighty-nine".
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