205821000 has 576 divisors, whose sum is σ = 906272640. Its totient is φ = 42768000.

The previous prime is 205820999. The next prime is 205821013. The reversal of 205821000 is 128502.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 18710995 + ... + 18711005.

It is an arithmetic number, because the mean of its divisors is an integer number (1573390).

Almost surely, 2^205821000 is an apocalyptic number.

205821000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 205821000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (453136320).

205821000 is an abundant number, since it is smaller than the sum of its proper divisors (700451640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

205821000 is a wasteful number, since it uses less digits than its factorization.

205821000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 205821000 is about 14346.4629787275. The cubic root of 205821000 is about 590.4229467583.

Adding to 205821000 its reverse (128502), we get a palindrome (205949502).

The spelling of 205821000 in words is "two hundred five million, eight hundred twenty-one thousand".