205020989 has 4 divisors (see below), whose sum is σ = 205051356. Its totient is φ = 204990624.

The previous prime is 205020973. The next prime is 205020997. The reversal of 205020989 is 989020502.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 989020502 = 2 ⋅494510251.

It can be written as a sum of positive squares in 2 ways, for example, as 137288089 + 67732900 = 11717^2 + 8230^2 .

It is a cyclic number.

It is not a de Polignac number, because 205020989 - 2⁴ = 205020973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205020889) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17 + ... + 20249.

It is an arithmetic number, because the mean of its divisors is an integer number (51262839).

Almost surely, 2^205020989 is an apocalyptic number.

It is an amenable number.

205020989 is a deficient number, since it is larger than the sum of its proper divisors (30367).

205020989 is a wasteful number, since it uses less digits than its factorization.

205020989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30366.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 205020989 is about 14318.5540121899. The cubic root of 205020989 is about 589.6569767053.

The spelling of 205020989 in words is "two hundred five million, twenty thousand, nine hundred eighty-nine".