208128913 has 4 divisors (see below), whose sum is σ = 210980068. Its totient is φ = 205277760.

The previous prime is 208128871. The next prime is 208128919. The reversal of 208128913 is 319821802.

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 152596609 + 55532304 = 12353^2 + 7452^2 .

It is a cyclic number.

It is not a de Polignac number, because 208128913 - 2¹⁷ = 207997841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (208128919) 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, 1425468 + ... + 1425613.

It is an arithmetic number, because the mean of its divisors is an integer number (52745017).

Almost surely, 2^208128913 is an apocalyptic number.

It is an amenable number.

208128913 is a deficient number, since it is larger than the sum of its proper divisors (2851155).

208128913 is an equidigital number, since it uses as much as digits as its factorization.

208128913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2851154.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 208128913 is about 14426.6736637383. The cubic root of 208128913 is about 592.6215936125.

The spelling of 208128913 in words is "two hundred eight million, one hundred twenty-eight thousand, nine hundred thirteen".