109581 has 4 divisors (see below), whose sum is σ = 146112. Its totient is φ = 73052.

The previous prime is 109579. The next prime is 109583. The reversal of 109581 is 185901.

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, and also an emirpimes, since its reverse is a distinct semiprime: 185901 = 3 ⋅61967.

It is an interprime number because it is at equal distance from previous prime (109579) and next prime (109583).

It is a cyclic number.

It is not a de Polignac number, because 109581 - 2¹ = 109579 is a prime.

It is a super-2 number, since 2×109581² = 24015991122, which contains 22 as substring.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (109583) 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, 18261 + ... + 18266.

It is an arithmetic number, because the mean of its divisors is an integer number (36528).

2¹⁰⁹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

109581 is a deficient number, since it is larger than the sum of its proper divisors (36531).

109581 is an equidigital number, since it uses as much as digits as its factorization.

109581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36530.

The product of its (nonzero) digits is 360, while the sum is 24.

The square root of 109581 is about 331.0302101017. The cubic root of 109581 is about 47.8532846501.

It can be divided in two parts, 1095 and 81, that added together give a triangular number (1176 = T₄₈).

The spelling of 109581 in words is "one hundred nine thousand, five hundred eighty-one".