195633991 has 4 divisors (see below), whose sum is σ = 223581712. Its totient is φ = 167686272.

The previous prime is 195633989. The next prime is 195634009. The reversal of 195633991 is 199336591.

195633991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199336591 = 67 ⋅2975173.

It is a cyclic number.

It is not a de Polignac number, because 195633991 - 2¹ = 195633989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (195633491) 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, 13973850 + ... + 13973863.

It is an arithmetic number, because the mean of its divisors is an integer number (55895428).

Almost surely, 2^195633991 is an apocalyptic number.

195633991 is a deficient number, since it is larger than the sum of its proper divisors (27947721).

195633991 is an equidigital number, since it uses as much as digits as its factorization.

195633991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27947720.

The product of its digits is 196830, while the sum is 46.

The square root of 195633991 is about 13986.9221417723. The cubic root of 195633991 is about 580.5167718881.

The spelling of 195633991 in words is "one hundred ninety-five million, six hundred thirty-three thousand, nine hundred ninety-one".