100809 has 12 divisors (see below), whose sum is σ = 152256. Its totient is φ = 64152.
The previous prime is 100801. The next prime is 100811. The reversal of 100809 is 908001.
It is not a de Polignac number, because 100809 - 23 = 100801 is a prime.
100809 is a lucky number.
It is a junction number, because it is equal to n+sod(n) for n = 100791 and 100800.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (100801) 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, 37 + ... + 450.
It is an arithmetic number, because the mean of its divisors is an integer number (12688).
2100809 is an apocalyptic number.
It is an amenable number.
100809 is a deficient number, since it is larger than the sum of its proper divisors (51447).
100809 is a wasteful number, since it uses less digits than its factorization.
100809 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 516 (or 513 counting only the distinct ones).
The product of its (nonzero) digits is 72, while the sum is 18.
The square root of 100809 is about 317.5043306791. The cubic root of 100809 is about 46.5407204871.
It can be divided in two parts, 100 and 809, that added together give a palindrome (909).
The spelling of 100809 in words is "one hundred thousand, eight hundred nine".
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