205199021 has 2 divisors, whose sum is σ = 205199022. Its totient is φ = 205199020.

The previous prime is 205199009. The next prime is 205199047. The reversal of 205199021 is 120991502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 186622921 + 18576100 = 13661^2 + 4310^2 .

It is a cyclic number.

It is not a de Polignac number, because 205199021 - 2²² = 201004717 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205099021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102599510 + 102599511.

It is an arithmetic number, because the mean of its divisors is an integer number (102599511).

Almost surely, 2^205199021 is an apocalyptic number.

It is an amenable number.

205199021 is a deficient number, since it is larger than the sum of its proper divisors (1).

205199021 is an equidigital number, since it uses as much as digits as its factorization.

205199021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 205199021 is about 14324.7694920372. The cubic root of 205199021 is about 589.8276054783.

The spelling of 205199021 in words is "two hundred five million, one hundred ninety-nine thousand, twenty-one".