198784897609 has 3 divisors (see below), whose sum is σ = 198785343463. Its totient is φ = 198784451756.

The previous prime is 198784897543. The next prime is 198784897669. The reversal of 198784897609 is 906798487891.

The square root of 198784897609 is 445853.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 135597015225 + 63187882384 = 368235^2 + 251372^2 .

It is not a de Polignac number, because 198784897609 - 2⁷ = 198784897481 is a prime.

It is a super-2 number, since 2×198784897609² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (198784897669) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 222927 + ... + 668779.

Almost surely, 2^198784897609 is an apocalyptic number.

198784897609 is the 445853-rd square number.

198784897609 is the 222927-th centered octagonal number.

It is an amenable number.

198784897609 is a deficient number, since it is larger than the sum of its proper divisors (445854).

198784897609 is an frugal number, since it uses more digits than its factorization.

198784897609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891706 (or 445853 counting only the distinct ones).

The product of its (nonzero) digits is 438939648, while the sum is 76.

The spelling of 198784897609 in words is "one hundred ninety-eight billion, seven hundred eighty-four million, eight hundred ninety-seven thousand, six hundred nine".