195520991 has 4 divisors (see below), whose sum is σ = 196815984. Its totient is φ = 194226000.

The previous prime is 195520981. The next prime is 195521009. The reversal of 195520991 is 199025591.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199025591 = 4339 ⋅45869.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-195520991 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 (195520901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 647270 + ... + 647571.

It is an arithmetic number, because the mean of its divisors is an integer number (49203996).

Almost surely, 2^195520991 is an apocalyptic number.

195520991 is a deficient number, since it is larger than the sum of its proper divisors (1294993).

195520991 is a wasteful number, since it uses less digits than its factorization.

195520991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1294992.

The product of its (nonzero) digits is 36450, while the sum is 41.

The square root of 195520991 is about 13982.8820705890. The cubic root of 195520991 is about 580.4049797450.

The spelling of 195520991 in words is "one hundred ninety-five million, five hundred twenty thousand, nine hundred ninety-one".