81975 has 12 divisors (see below), whose sum is σ = 135656. Its totient is φ = 43680.
The previous prime is 81973. The next prime is 82003. The reversal of 81975 is 57918.
It is not a de Polignac number, because 81975 - 21 = 81973 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (81971) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 472 + ... + 621.
281975 is an apocalyptic number.
81975 is a deficient number, since it is larger than the sum of its proper divisors (53681).
81975 is a wasteful number, since it uses less digits than its factorization.
81975 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 1106 (or 1101 counting only the distinct ones).
The product of its digits is 2520, while the sum is 30.
The square root of 81975 is about 286.3127660444. The cubic root of 81975 is about 43.4403992855.
It can be divided in two parts, 819 and 75, that multiplied together give a triangular number (61425 = T350).
The spelling of 81975 in words is "eighty-one thousand, nine hundred seventy-five".
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