207728009 has 4 divisors (see below), whose sum is σ = 207769620. Its totient is φ = 207686400.

The previous prime is 207727999. The next prime is 207728033. The reversal of 207728009 is 900827702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 900827702 = 2 ⋅450413851.

It can be written as a sum of positive squares in 2 ways, for example, as 167443600 + 40284409 = 12940^2 + 6347^2 .

It is a cyclic number.

It is not a de Polignac number, because 207728009 - 2¹² = 207723913 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 207728009.

It is not an unprimeable number, because it can be changed into a prime (207728809) 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 3 ways as a sum of consecutive naturals, for example, 12104 + ... + 23705.

It is an arithmetic number, because the mean of its divisors is an integer number (51942405).

Almost surely, 2^207728009 is an apocalyptic number.

It is an amenable number.

207728009 is a deficient number, since it is larger than the sum of its proper divisors (41611).

207728009 is an equidigital number, since it uses as much as digits as its factorization.

207728009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41610.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 207728009 is about 14412.7724258728. The cubic root of 207728009 is about 592.2408406860.

The spelling of 207728009 in words is "two hundred seven million, seven hundred twenty-eight thousand, nine".