117781 has 4 divisors (see below), whose sum is σ = 124000. Its totient is φ = 111564.

The previous prime is 117779. The next prime is 117787. The reversal of 117781 is 187711.

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 117781 - 2¹ = 117779 is a prime.

It is a super-2 number, since 2×117781² = 27744727922, 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 (117787) 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, 3081 + ... + 3118.

It is an arithmetic number, because the mean of its divisors is an integer number (31000).

2¹¹⁷⁷⁸¹ is an apocalyptic number.

It is an amenable number.

117781 is a deficient number, since it is larger than the sum of its proper divisors (6219).

117781 is an equidigital number, since it uses as much as digits as its factorization.

117781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6218.

The product of its digits is 392, while the sum is 25.

The square root of 117781 is about 343.1923658825. The cubic root of 117781 is about 49.0183188482.

It can be divided in two parts, 117 and 781, that added together give a palindrome (898).

The spelling of 117781 in words is "one hundred seventeen thousand, seven hundred eighty-one".