204851 has 4 divisors (see below), whose sum is σ = 206592. Its totient is φ = 203112.

The previous prime is 204821. The next prime is 204857. The reversal of 204851 is 158402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 158402 = 2 ⋅79201.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (204857) 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 3 ways as a sum of consecutive naturals, for example, 680 + ... + 933.

It is an arithmetic number, because the mean of its divisors is an integer number (51648).

2²⁰⁴⁸⁵¹ is an apocalyptic number.

204851 is a deficient number, since it is larger than the sum of its proper divisors (1741).

204851 is a wasteful number, since it uses less digits than its factorization.

204851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 204851 is about 452.6046840235. The cubic root of 204851 is about 58.9493964265.

It can be divided in two parts, 20 and 4851, that multiplied together give a triangular number (97020 = T₄₄₀).

The spelling of 204851 in words is "two hundred four thousand, eight hundred fifty-one".