208974856781 has 2 divisors, whose sum is σ = 208974856782. Its totient is φ = 208974856780.

The previous prime is 208974856759. The next prime is 208974856793. The reversal of 208974856781 is 187658479802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 146803922500 + 62170934281 = 383150^2 + 249341^2 .

It is a cyclic number.

It is not a de Polignac number, because 208974856781 - 2¹⁴ = 208974840397 is a prime.

It is a super-2 number, since 2×208974856781² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208974856481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104487428390 + 104487428391.

It is an arithmetic number, because the mean of its divisors is an integer number (104487428391).

Almost surely, 2^208974856781 is an apocalyptic number.

It is an amenable number.

208974856781 is a deficient number, since it is larger than the sum of its proper divisors (1).

208974856781 is an equidigital number, since it uses as much as digits as its factorization.

208974856781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54190080, while the sum is 65.

The spelling of 208974856781 in words is "two hundred eight billion, nine hundred seventy-four million, eight hundred fifty-six thousand, seven hundred eighty-one".