291561 has 4 divisors (see below), whose sum is σ = 388752. Its totient is φ = 194372.

The previous prime is 291559. The next prime is 291563. The reversal of 291561 is 165192.

291561 is nontrivially palindromic in base 13.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (291559) and next prime (291563).

It is a cyclic number.

It is not a de Polignac number, because 291561 - 2¹ = 291559 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (291563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48591 + ... + 48596.

It is an arithmetic number, because the mean of its divisors is an integer number (97188).

2²⁹¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

291561 is a deficient number, since it is larger than the sum of its proper divisors (97191).

291561 is an equidigital number, since it uses as much as digits as its factorization.

291561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97190.

The product of its digits is 540, while the sum is 24.

The square root of 291561 is about 539.9638876814. The cubic root of 291561 is about 66.3096105221.

The spelling of 291561 in words is "two hundred ninety-one thousand, five hundred sixty-one".