81431 has 4 divisors (see below), whose sum is σ = 93072. Its totient is φ = 69792.
The previous prime is 81421. The next prime is 81439. The reversal of 81431 is 13418.
It is a happy number.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13418 = 2 ⋅6709.
It is a cyclic number.
It is not a de Polignac number, because 81431 - 210 = 80407 is a prime.
It is a super-2 number, since 2×814312 = 13262015522, which contains 22 as substring.
It is a congruent number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81431.
It is not an unprimeable number, because it can be changed into a prime (81439) 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, 5810 + ... + 5823.
It is an arithmetic number, because the mean of its divisors is an integer number (23268).
281431 is an apocalyptic number.
81431 is a deficient number, since it is larger than the sum of its proper divisors (11641).
81431 is a wasteful number, since it uses less digits than its factorization.
81431 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 11640.
The product of its digits is 96, while the sum is 17.
The square root of 81431 is about 285.3611746542. The cubic root of 81431 is about 43.3440933175.
Adding to 81431 its reverse (13418), we get a palindrome (94849).
It can be divided in two parts, 81 and 431, that added together give a 9-th power (512 = 29).
The spelling of 81431 in words is "eighty-one thousand, four hundred thirty-one".
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