291987 has 6 divisors (see below), whose sum is σ = 421772. Its totient is φ = 194652.

The previous prime is 291983. The next prime is 291997. The reversal of 291987 is 789192.

It is a happy number.

It is not a de Polignac number, because 291987 - 2² = 291983 is a prime.

It is a Duffinian number.

291987 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 291987.

It is not an unprimeable number, because it can be changed into a prime (291983) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 16213 + ... + 16230.

2²⁹¹⁹⁸⁷ is an apocalyptic number.

291987 is a deficient number, since it is larger than the sum of its proper divisors (129785).

291987 is a wasteful number, since it uses less digits than its factorization.

291987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32449 (or 32446 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 291987 is about 540.3582145207. The cubic root of 291987 is about 66.3418898137.

It can be divided in two parts, 29 and 1987, that added together give a triangular number (2016 = T₆₃).

The spelling of 291987 in words is "two hundred ninety-one thousand, nine hundred eighty-seven".