109561 has 3 divisors (see below), whose sum is σ = 109893. Its totient is φ = 109230.

The previous prime is 109547. The next prime is 109567. The reversal of 109561 is 165901.

109561 = T₃₃₀ + T₃₃₁.

The square root of 109561 is 331.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 109561 - 2⁷ = 109433 is a prime.

It is a super-2 number, since 2×109561² = 24007225442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (109567) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 166 + ... + 496.

It is an arithmetic number, because the mean of its divisors is an integer number (36631).

2¹⁰⁹⁵⁶¹ is an apocalyptic number.

109561 is the 331-st square number.

109561 is the 166-th centered octagonal number.

It is an amenable number.

109561 is a deficient number, since it is larger than the sum of its proper divisors (332).

109561 is an frugal number, since it uses more digits than its factorization.

109561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662 (or 331 counting only the distinct ones).

The product of its (nonzero) digits is 270, while the sum is 22.

The cubic root of 109561 is about 47.8503731845.

It can be divided in two parts, 1095 and 61, that multiplied together give a triangular number (66795 = T₃₆₅).

The spelling of 109561 in words is "one hundred nine thousand, five hundred sixty-one".