205500021 has 8 divisors (see below), whose sum is σ = 277079040. Its totient is φ = 135460512.

The previous prime is 205500017. The next prime is 205500041. The reversal of 205500021 is 120005502.

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

It is not a de Polignac number, because 205500021 - 2² = 205500017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205500041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384565 + ... + 385098.

It is an arithmetic number, because the mean of its divisors is an integer number (34634880).

Almost surely, 2^205500021 is an apocalyptic number.

It is an amenable number.

205500021 is a deficient number, since it is larger than the sum of its proper divisors (71579019).

205500021 is an equidigital number, since it uses as much as digits as its factorization.

205500021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769755.

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 205500021 is about 14335.2719192905. The cubic root of 205500021 is about 590.1158644422.

Adding to 205500021 its reverse (120005502), we get a palindrome (325505523).

The spelling of 205500021 in words is "two hundred five million, five hundred thousand, twenty-one".