1020206665 has 4 divisors (see below), whose sum is σ = 1224248004. Its totient is φ = 816165328.

The previous prime is 1020206641. The next prime is 1020206717. The reversal of 1020206665 is 5666020201.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 292717881 + 727488784 = 17109^2 + 26972^2 .

It is a cyclic number.

It is not a de Polignac number, because 1020206665 - 2⁹ = 1020206153 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102020662 + ... + 102020671.

It is an arithmetic number, because the mean of its divisors is an integer number (306062001).

Almost surely, 2^1020206665 is an apocalyptic number.

It is an amenable number.

1020206665 is a deficient number, since it is larger than the sum of its proper divisors (204041339).

1020206665 is an equidigital number, since it uses as much as digits as its factorization.

1020206665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204041338.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1020206665 is about 31940.6741475505. The cubic root of 1020206665 is about 1006.6906898326.

Adding to 1020206665 its reverse (5666020201), we get a palindrome (6686226866).

The spelling of 1020206665 in words is "one billion, twenty million, two hundred six thousand, six hundred sixty-five".