205984861 has 8 divisors (see below), whose sum is σ = 214470648. Its totient is φ = 197664000.

The previous prime is 205984841. The next prime is 205984873. The reversal of 205984861 is 168489502.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4884100 + 201100761 = 2210^2 + 14181^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 205984861 - 2⁵ = 205984829 is a prime.

It is a super-2 number, since 2×205984861² = 84859525922378642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205984841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38680 + ... + 43681.

It is an arithmetic number, because the mean of its divisors is an integer number (26808831).

Almost surely, 2^205984861 is an apocalyptic number.

It is an amenable number.

205984861 is a deficient number, since it is larger than the sum of its proper divisors (8485787).

205984861 is an equidigital number, since it uses as much as digits as its factorization.

205984861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82463.

The product of its (nonzero) digits is 138240, while the sum is 43.

The square root of 205984861 is about 14352.1726926623. The cubic root of 205984861 is about 590.5795903649.

The spelling of 205984861 in words is "two hundred five million, nine hundred eighty-four thousand, eight hundred sixty-one".