117661 has 4 divisors (see below), whose sum is σ = 118972. Its totient is φ = 116352.

The previous prime is 117659. The next prime is 117671. The reversal of 117661 is 166711.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166711 = 43 ⋅3877.

It can be written as a sum of positive squares in 2 ways, for example, as 24025 + 93636 = 155^2 + 306^2 .

It is a cyclic number.

It is not a de Polignac number, because 117661 - 2¹ = 117659 is a prime.

It is a super-2 number, since 2×117661² = 27688221842, 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 (117671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 510 + ... + 703.

It is an arithmetic number, because the mean of its divisors is an integer number (29743).

117661 is a Friedman number, since it can be written as 7^6+6*1*(1+1), using all its digits and the basic arithmetic operations.

2¹¹⁷⁶⁶¹ is an apocalyptic number.

It is an amenable number.

117661 is a deficient number, since it is larger than the sum of its proper divisors (1311).

117661 is an equidigital number, since it uses as much as digits as its factorization.

117661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1310.

The product of its digits is 252, while the sum is 22.

The square root of 117661 is about 343.0174922653. The cubic root of 117661 is about 49.0016659159.

The spelling of 117661 in words is "one hundred seventeen thousand, six hundred sixty-one".