191923987 has 4 divisors (see below), whose sum is σ = 192654000. Its totient is φ = 191193976.

The previous prime is 191923973. The next prime is 191924003. The reversal of 191923987 is 789329191.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191923987 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 191923987.

It is not an unprimeable number, because it can be changed into a prime (191923957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364612 + ... + 365137.

It is an arithmetic number, because the mean of its divisors is an integer number (48163500).

Almost surely, 2^191923987 is an apocalyptic number.

191923987 is a deficient number, since it is larger than the sum of its proper divisors (730013).

191923987 is an equidigital number, since it uses as much as digits as its factorization.

191923987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 730012.

The product of its digits is 244944, while the sum is 49.

The square root of 191923987 is about 13853.6633061440. The cubic root of 191923987 is about 576.8236863262.

The spelling of 191923987 in words is "one hundred ninety-one million, nine hundred twenty-three thousand, nine hundred eighty-seven".