155666165 has 4 divisors (see below), whose sum is σ = 186799404. Its totient is φ = 124532928.

The previous prime is 155666143. The next prime is 155666167. The reversal of 155666165 is 561666551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 561666551 = 11243 ⋅49957.

It can be written as a sum of positive squares in 2 ways, for example, as 80982001 + 74684164 = 8999^2 + 8642^2 .

It is a cyclic number.

It is not a de Polignac number, because 155666165 - 2⁶ = 155666101 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155666167) 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, 15566612 + ... + 15566621.

It is an arithmetic number, because the mean of its divisors is an integer number (46699851).

Almost surely, 2^155666165 is an apocalyptic number.

It is an amenable number.

155666165 is a deficient number, since it is larger than the sum of its proper divisors (31133239).

155666165 is an equidigital number, since it uses as much as digits as its factorization.

155666165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31133238.

The product of its digits is 162000, while the sum is 41.

The square root of 155666165 is about 12476.6247438961. The cubic root of 155666165 is about 537.9369902207.

The spelling of 155666165 in words is "one hundred fifty-five million, six hundred sixty-six thousand, one hundred sixty-five".