109781 has 4 divisors (see below), whose sum is σ = 125472. Its totient is φ = 94092.

The previous prime is 109751. The next prime is 109789. The reversal of 109781 is 187901.

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.

It is a cyclic number.

It is not a de Polignac number, because 109781 - 2⁶ = 109717 is a prime.

It is a super-2 number, since 2×109781² = 24103735922, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 109781.

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 109781.

It is not an unprimeable number, because it can be changed into a prime (109789) 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, 7835 + ... + 7848.

It is an arithmetic number, because the mean of its divisors is an integer number (31368).

2¹⁰⁹⁷⁸¹ is an apocalyptic number.

It is an amenable number.

109781 is a deficient number, since it is larger than the sum of its proper divisors (15691).

109781 is an equidigital number, since it uses as much as digits as its factorization.

109781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15690.

The product of its (nonzero) digits is 504, while the sum is 26.

The square root of 109781 is about 331.3321596223. The cubic root of 109781 is about 47.8823798407.

The spelling of 109781 in words is "one hundred nine thousand, seven hundred eighty-one".