156665 has 4 divisors (see below), whose sum is σ = 188004. Its totient is φ = 125328.

The previous prime is 156659. The next prime is 156671. The reversal of 156665 is 566651.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (156659) and next prime (156671).

It can be written as a sum of positive squares in 2 ways, for example, as 123904 + 32761 = 352^2 + 181^2 .

It is a cyclic number.

It is not a de Polignac number, because 156665 - 2⁶ = 156601 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

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, 15662 + ... + 15671.

It is an arithmetic number, because the mean of its divisors is an integer number (47001).

2¹⁵⁶⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

156665 is a deficient number, since it is larger than the sum of its proper divisors (31339).

156665 is an equidigital number, since it uses as much as digits as its factorization.

156665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31338.

The product of its digits is 5400, while the sum is 29.

The square root of 156665 is about 395.8092975159. The cubic root of 156665 is about 53.9085099172.

It can be divided in two parts, 156 and 665, that multiplied together give a triangular number (103740 = T₄₅₅).

The spelling of 156665 in words is "one hundred fifty-six thousand, six hundred sixty-five".