198707521 has 4 divisors (see below), whose sum is σ = 199973332. Its totient is φ = 197441712.

The previous prime is 198707519. The next prime is 198707539. The reversal of 198707521 is 125707891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125707891 = 53 ⋅2371847.

It can be written as a sum of positive squares in 2 ways, for example, as 16160400 + 182547121 = 4020^2 + 13511^2 .

It is a cyclic number.

It is not a de Polignac number, because 198707521 - 2¹ = 198707519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (198707581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 632670 + ... + 632983.

It is an arithmetic number, because the mean of its divisors is an integer number (49993333).

Almost surely, 2^198707521 is an apocalyptic number.

It is an amenable number.

198707521 is a deficient number, since it is larger than the sum of its proper divisors (1265811).

198707521 is a wasteful number, since it uses less digits than its factorization.

198707521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1265810.

The product of its (nonzero) digits is 35280, while the sum is 40.

The square root of 198707521 is about 14096.3655244889. The cubic root of 198707521 is about 583.5410803629.

The spelling of 198707521 in words is "one hundred ninety-eight million, seven hundred seven thousand, five hundred twenty-one".