291185987 has 2 divisors, whose sum is σ = 291185988. Its totient is φ = 291185986.

The previous prime is 291185959. The next prime is 291185989. The reversal of 291185987 is 789581192.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 291185987 - 2²⁶ = 224077123 is a prime.

Together with 291185989, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (291185989) 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 as a sum of consecutive naturals, namely, 145592993 + 145592994.

It is an arithmetic number, because the mean of its divisors is an integer number (145592994).

Almost surely, 2^291185987 is an apocalyptic number.

291185987 is a deficient number, since it is larger than the sum of its proper divisors (1).

291185987 is an equidigital number, since it uses as much as digits as its factorization.

291185987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 50.

The square root of 291185987 is about 17064.1726139886. The cubic root of 291185987 is about 662.8116863509.

The spelling of 291185987 in words is "two hundred ninety-one million, one hundred eighty-five thousand, nine hundred eighty-seven".