198289781 has 2 divisors, whose sum is σ = 198289782. Its totient is φ = 198289780.

The previous prime is 198289709. The next prime is 198289807. The reversal of 198289781 is 187982891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134768881 + 63520900 = 11609^2 + 7970^2 .

It is a cyclic number.

It is not a de Polignac number, because 198289781 - 2¹⁰ = 198288757 is a prime.

It is a super-2 number, since 2×198289781² = 78637674498055922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198289081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99144890 + 99144891.

It is an arithmetic number, because the mean of its divisors is an integer number (99144891).

Almost surely, 2^198289781 is an apocalyptic number.

It is an amenable number.

198289781 is a deficient number, since it is larger than the sum of its proper divisors (1).

198289781 is an equidigital number, since it uses as much as digits as its factorization.

198289781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608, while the sum is 53.

The square root of 198289781 is about 14081.5404341997. The cubic root of 198289781 is about 583.1318700939.

The spelling of 198289781 in words is "one hundred ninety-eight million, two hundred eighty-nine thousand, seven hundred eighty-one".