291005 has 24 divisors (see below), whose sum is σ = 424536. Its totient is φ = 190080.

The previous prime is 290999. The next prime is 291007. The reversal of 291005 is 500192.

It can be written as a sum of positive squares in 4 ways, for example, as 34969 + 256036 = 187^2 + 506^2 .

It is a de Polignac number, because none of the positive numbers 2^k-291005 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 291005.

It is not an unprimeable number, because it can be changed into a prime (291007) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7847 + ... + 7883.

It is an arithmetic number, because the mean of its divisors is an integer number (17689).

2²⁹¹⁰⁰⁵ is an apocalyptic number.

It is an amenable number.

291005 is a deficient number, since it is larger than the sum of its proper divisors (133531).

291005 is a wasteful number, since it uses less digits than its factorization.

291005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77 (or 66 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 291005 is about 539.4487927505. The cubic root of 291005 is about 66.2674334090.

Multiplying 291005 by its sum of digits (17), we get a triangular number (4947085 = T₃₁₄₅).

Adding to 291005 its reverse (500192), we get a palindrome (791197).

The spelling of 291005 in words is "two hundred ninety-one thousand, five".