208847072821 has 4 divisors (see below), whose sum is σ = 208848778732. Its totient is φ = 208845366912.

The previous prime is 208847072813. The next prime is 208847072851. The reversal of 208847072821 is 128270748802.

It is a happy number.

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 18724911921 + 190122160900 = 136839^2 + 436030^2 .

It is a cyclic number.

It is not a de Polignac number, because 208847072821 - 2³ = 208847072813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (208847072851) 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, 653820 + ... + 919333.

It is an arithmetic number, because the mean of its divisors is an integer number (52212194683).

Almost surely, 2^208847072821 is an apocalyptic number.

It is an amenable number.

208847072821 is a deficient number, since it is larger than the sum of its proper divisors (1705911).

208847072821 is a wasteful number, since it uses less digits than its factorization.

208847072821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1705910.

The product of its (nonzero) digits is 802816, while the sum is 49.

The spelling of 208847072821 in words is "two hundred eight billion, eight hundred forty-seven million, seventy-two thousand, eight hundred twenty-one".