198591387 has 4 divisors (see below), whose sum is σ = 264788520. Its totient is φ = 132394256.

The previous prime is 198591373. The next prime is 198591389. The reversal of 198591387 is 783195891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 783195891 = 3 ⋅261065297.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198591387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (198591389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33098562 + ... + 33098567.

It is an arithmetic number, because the mean of its divisors is an integer number (66197130).

Almost surely, 2^198591387 is an apocalyptic number.

198591387 is a deficient number, since it is larger than the sum of its proper divisors (66197133).

198591387 is an equidigital number, since it uses as much as digits as its factorization.

198591387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66197132.

The product of its digits is 544320, while the sum is 51.

The square root of 198591387 is about 14092.2456336810. The cubic root of 198591387 is about 583.4273752781.

The spelling of 198591387 in words is "one hundred ninety-eight million, five hundred ninety-one thousand, three hundred eighty-seven".