208416774821 has 2 divisors, whose sum is σ = 208416774822. Its totient is φ = 208416774820.

The previous prime is 208416774749. The next prime is 208416774823. The reversal of 208416774821 is 128477614802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 131704393921 + 76712380900 = 362911^2 + 276970^2 .

It is a cyclic number.

It is not a de Polignac number, because 208416774821 - 2¹⁰ = 208416773797 is a prime.

Together with 208416774823, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 208416774821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208416774823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104208387410 + 104208387411.

It is an arithmetic number, because the mean of its divisors is an integer number (104208387411).

Almost surely, 2^208416774821 is an apocalyptic number.

It is an amenable number.

208416774821 is a deficient number, since it is larger than the sum of its proper divisors (1).

208416774821 is an equidigital number, since it uses as much as digits as its factorization.

208416774821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1204224, while the sum is 50.

The spelling of 208416774821 in words is "two hundred eight billion, four hundred sixteen million, seven hundred seventy-four thousand, eight hundred twenty-one".