194505009781 has 2 divisors, whose sum is σ = 194505009782. Its totient is φ = 194505009780.

The previous prime is 194505009767. The next prime is 194505009793. The reversal of 194505009781 is 187900505491.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 145946920900 + 48558088881 = 382030^2 + 220359^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-194505009781 is a prime.

It is a super-3 number, since 3×194505009781³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (194505019781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97252504890 + 97252504891.

It is an arithmetic number, because the mean of its divisors is an integer number (97252504891).

Almost surely, 2^194505009781 is an apocalyptic number.

It is an amenable number.

194505009781 is a deficient number, since it is larger than the sum of its proper divisors (1).

194505009781 is an equidigital number, since it uses as much as digits as its factorization.

194505009781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 453600, while the sum is 49.

The spelling of 194505009781 in words is "one hundred ninety-four billion, five hundred five million, nine thousand, seven hundred eighty-one".