108781 has 4 divisors (see below), whose sum is σ = 109564. Its totient is φ = 108000.

The previous prime is 108769. The next prime is 108791. The reversal of 108781 is 187801.

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, and also an emirpimes, since its reverse is a distinct semiprime: 187801 = 67 ⋅2803.

It can be written as a sum of positive squares in 2 ways, for example, as 38025 + 70756 = 195^2 + 266^2 .

It is a 3-Lehmer number, since φ(108781) divides (108781-1)³.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-108781 is a prime.

It is a super-2 number, since 2×108781² = 23666611922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (108751) 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, 120 + ... + 481.

It is an arithmetic number, because the mean of its divisors is an integer number (27391).

2¹⁰⁸⁷⁸¹ is an apocalyptic number.

108781 is the 148-th centered decagonal number.

It is an amenable number.

108781 is a deficient number, since it is larger than the sum of its proper divisors (783).

108781 is an equidigital number, since it uses as much as digits as its factorization.

108781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782.

The product of its (nonzero) digits is 448, while the sum is 25.

The square root of 108781 is about 329.8196476864. The cubic root of 108781 is about 47.7365485716.

It can be divided in two parts, 108 and 781, that multiplied together give a palindrome (84348).

The spelling of 108781 in words is "one hundred eight thousand, seven hundred eighty-one".