205100021 has 8 divisors (see below), whose sum is σ = 234489024. Its totient is φ = 175733280.

The previous prime is 205100011. The next prime is 205100069. The reversal of 205100021 is 120001502.

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 205100021 - 2¹⁰ = 205098997 is a prime.

It is a super-2 number, since 2×205100021² = 84132037228400882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 205099975 and 205100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205100011) 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, 26561 + ... + 33401.

It is an arithmetic number, because the mean of its divisors is an integer number (29311128).

Almost surely, 2^205100021 is an apocalyptic number.

It is an amenable number.

205100021 is a deficient number, since it is larger than the sum of its proper divisors (29389003).

205100021 is an equidigital number, since it uses as much as digits as its factorization.

205100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11131.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 205100021 is about 14321.3135221599. The cubic root of 205100021 is about 589.7327344503.

Adding to 205100021 its reverse (120001502), we get a palindrome (325101523).

The spelling of 205100021 in words is "two hundred five million, one hundred thousand, twenty-one".