191888987 has 2 divisors, whose sum is σ = 191888988. Its totient is φ = 191888986.

The previous prime is 191888959. The next prime is 191889001. The reversal of 191888987 is 789888191.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (789888191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191888987 - 2¹⁰ = 191887963 is a prime.

It is not a weakly prime, because it can be changed into another prime (191888927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95944493 + 95944494.

It is an arithmetic number, because the mean of its divisors is an integer number (95944494).

Almost surely, 2^191888987 is an apocalyptic number.

191888987 is a deficient number, since it is larger than the sum of its proper divisors (1).

191888987 is an equidigital number, since it uses as much as digits as its factorization.

191888987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2322432, while the sum is 59.

The square root of 191888987 is about 13852.4000447576. The cubic root of 191888987 is about 576.7886202623.

The spelling of 191888987 in words is "one hundred ninety-one million, eight hundred eighty-eight thousand, nine hundred eighty-seven".