206720665 has 32 divisors (see below), whose sum is σ = 279947520. Its totient is φ = 145753344.

The previous prime is 206720611. The next prime is 206720669. The reversal of 206720665 is 566027602.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206720665 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 206720665.

It is not an unprimeable number, because it can be changed into a prime (206720669) 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 31 ways as a sum of consecutive naturals, for example, 79567 + ... + 82123.

It is an arithmetic number, because the mean of its divisors is an integer number (8748360).

Almost surely, 2^206720665 is an apocalyptic number.

It is an amenable number.

206720665 is a deficient number, since it is larger than the sum of its proper divisors (73226855).

206720665 is a wasteful number, since it uses less digits than its factorization.

206720665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2641.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 206720665 is about 14377.7837304642. The cubic root of 206720665 is about 591.2819630598.

The spelling of 206720665 in words is "two hundred six million, seven hundred twenty thousand, six hundred sixty-five".