194861979857 has 2 divisors, whose sum is σ = 194861979858. Its totient is φ = 194861979856.

The previous prime is 194861979779. The next prime is 194861979859. The reversal of 194861979857 is 758979168491.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 119107124161 + 75754855696 = 345119^2 + 275236^2 .

It is a cyclic number.

It is not a de Polignac number, because 194861979857 - 2¹² = 194861975761 is a prime.

Together with 194861979859, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (194861979859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97430989928 + 97430989929.

It is an arithmetic number, because the mean of its divisors is an integer number (97430989929).

Almost surely, 2^194861979857 is an apocalyptic number.

It is an amenable number.

194861979857 is a deficient number, since it is larger than the sum of its proper divisors (1).

194861979857 is an equidigital number, since it uses as much as digits as its factorization.

194861979857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 274337280, while the sum is 74.

The spelling of 194861979857 in words is "one hundred ninety-four billion, eight hundred sixty-one million, nine hundred seventy-nine thousand, eight hundred fifty-seven".