198400756781 has 2 divisors, whose sum is σ = 198400756782. Its totient is φ = 198400756780.

The previous prime is 198400756709. The next prime is 198400756787. The reversal of 198400756781 is 187657004891.

It is a happy number.

198400756781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 102378241156 + 96022515625 = 319966^2 + 309875^2 .

It is a cyclic number.

It is not a de Polignac number, because 198400756781 - 2¹⁸ = 198400494637 is a prime.

It is a super-2 number, since 2×198400756781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198400756787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99200378390 + 99200378391.

It is an arithmetic number, because the mean of its divisors is an integer number (99200378391).

Almost surely, 2^198400756781 is an apocalyptic number.

It is an amenable number.

198400756781 is a deficient number, since it is larger than the sum of its proper divisors (1).

198400756781 is an equidigital number, since it uses as much as digits as its factorization.

198400756781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3386880, while the sum is 56.

The spelling of 198400756781 in words is "one hundred ninety-eight billion, four hundred million, seven hundred fifty-six thousand, seven hundred eighty-one".