291081987 has 24 divisors (see below), whose sum is σ = 488666880. Its totient is φ = 163511280.

The previous prime is 291081979. The next prime is 291082009. The reversal of 291081987 is 789180192.

It is not a de Polignac number, because 291081987 - 2³ = 291081979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (291081937) 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 23 ways as a sum of consecutive naturals, for example, 35439 + ... + 42872.

It is an arithmetic number, because the mean of its divisors is an integer number (20361120).

Almost surely, 2^291081987 is an apocalyptic number.

291081987 is a deficient number, since it is larger than the sum of its proper divisors (197584893).

291081987 is a wasteful number, since it uses less digits than its factorization.

291081987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78383 (or 78380 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 45.

The square root of 291081987 is about 17061.1250215219. The cubic root of 291081987 is about 662.7327670041.

The spelling of 291081987 in words is "two hundred ninety-one million, eighty-one thousand, nine hundred eighty-seven".