208509479672831 has 4 divisors (see below), whose sum is σ = 213595076738064. Its totient is φ = 203423882607600.

The previous prime is 208509479672801. The next prime is 208509479672843. The reversal of 208509479672831 is 138276974905802.

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

It is a cyclic number.

It is not a de Polignac number, because 208509479672831 - 2¹⁰ = 208509479671807 is a prime.

It is a super-2 number, since 2×208509479672831² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (208509479672801) 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, 2542798532555 + ... + 2542798532636.

It is an arithmetic number, because the mean of its divisors is an integer number (53398769184516).

It is a 2-persistent number, because it is pandigital, and so is 2⋅208509479672831 = 417018959345662, but 3⋅208509479672831 = 625528439018493 is not.

Almost surely, 2^{208509479672831} is an apocalyptic number.

208509479672831 is a deficient number, since it is larger than the sum of its proper divisors (5085597065233).

208509479672831 is an equidigital number, since it uses as much as digits as its factorization.

208509479672831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5085597065232.

The product of its (nonzero) digits is 365783040, while the sum is 71.

The spelling of 208509479672831 in words is "two hundred eight trillion, five hundred nine billion, four hundred seventy-nine million, six hundred seventy-two thousand, eight hundred thirty-one".