205105421 has 8 divisors (see below), whose sum is σ = 214182144. Its totient is φ = 196042000.

The previous prime is 205105379. The next prime is 205105427. The reversal of 205105421 is 124501502.

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 205105421 - 2¹⁰ = 205104397 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 205105393 and 205105402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205105427) 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, 40796 + ... + 45546.

It is an arithmetic number, because the mean of its divisors is an integer number (26772768).

Almost surely, 2^205105421 is an apocalyptic number.

It is an amenable number.

205105421 is a deficient number, since it is larger than the sum of its proper divisors (9076723).

205105421 is a wasteful number, since it uses less digits than its factorization.

205105421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6651.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 205105421 is about 14321.5020511118. The cubic root of 205105421 is about 589.7379100207.

Adding to 205105421 its reverse (124501502), we get a palindrome (329606923).

The spelling of 205105421 in words is "two hundred five million, one hundred five thousand, four hundred twenty-one".