204921 has 6 divisors (see below), whose sum is σ = 296010. Its totient is φ = 136608.
The previous prime is 204917. The next prime is 204923. The reversal of 204921 is 129402.
It can be written as a sum of positive squares in only one way, i.e., 114921 + 90000 = 339^2 + 300^2 .
It is not a de Polignac number, because 204921 - 22 = 204917 is a prime.
204921 is a lucky number.
It is a junction number, because it is equal to n+sod(n) for n = 204894 and 204903.
It is not an unprimeable number, because it can be changed into a prime (204923) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11376 + ... + 11393.
It is an arithmetic number, because the mean of its divisors is an integer number (49335).
2204921 is an apocalyptic number.
It is an amenable number.
204921 is a deficient number, since it is larger than the sum of its proper divisors (91089).
204921 is a wasteful number, since it uses less digits than its factorization.
204921 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 22775 (or 22772 counting only the distinct ones).
The product of its (nonzero) digits is 144, while the sum is 18.
The square root of 204921 is about 452.6820075947. The cubic root of 204921 is about 58.9561102296.
The spelling of 204921 in words is "two hundred four thousand, nine hundred twenty-one".
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