291861 has 6 divisors (see below), whose sum is σ = 421590. Its totient is φ = 194568.

The previous prime is 291857. The next prime is 291869. The reversal of 291861 is 168192.

It can be written as a sum of positive squares in only one way, i.e., 269361 + 22500 = 519^2 + 150^2 .

It is not a de Polignac number, because 291861 - 2² = 291857 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (291869) 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, 16206 + ... + 16223.

It is an arithmetic number, because the mean of its divisors is an integer number (70265).

2²⁹¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

291861 is a deficient number, since it is larger than the sum of its proper divisors (129729).

291861 is a wasteful number, since it uses less digits than its factorization.

291861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32435 (or 32432 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 291861 is about 540.2416126142. The cubic root of 291861 is about 66.3323456892.

The spelling of 291861 in words is "two hundred ninety-one thousand, eight hundred sixty-one".