243581 has 8 divisors (see below), whose sum is σ = 269304. Its totient is φ = 218880.

The previous prime is 243577. The next prime is 243583. The reversal of 243581 is 185342.

243581 = 84² + 85² + ... + 109².

It can be written as a sum of positive squares in 4 ways, for example, as 3481 + 240100 = 59^2 + 490^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 243581 - 2² = 243577 is a prime.

It is a super-2 number, since 2×243581² = 118663407122, which contains 22 as substring.

It is a Duffinian 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 243581.

It is not an unprimeable number, because it can be changed into a prime (243583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 305 + ... + 761.

It is an arithmetic number, because the mean of its divisors is an integer number (33663).

2²⁴³⁵⁸¹ is an apocalyptic number.

It is an amenable number.

243581 is a deficient number, since it is larger than the sum of its proper divisors (25723).

243581 is a wasteful number, since it uses less digits than its factorization.

243581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511.

The product of its digits is 960, while the sum is 23.

The square root of 243581 is about 493.5392588234. The cubic root of 243581 is about 62.4522087987.

The spelling of 243581 in words is "two hundred forty-three thousand, five hundred eighty-one".