168618661 has 4 divisors (see below), whose sum is σ = 168671212. Its totient is φ = 168566112.

The previous prime is 168618643. The next prime is 168618677. The reversal of 168618661 is 166816861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166816861 = 23 ⋅7252907.

It can be written as a sum of positive squares in 2 ways, for example, as 109620900 + 58997761 = 10470^2 + 7681^2 .

It is a cyclic number.

It is not a de Polignac number, because 168618661 - 2⁵ = 168618629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168618061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21126 + ... + 27991.

It is an arithmetic number, because the mean of its divisors is an integer number (42167803).

Almost surely, 2^168618661 is an apocalyptic number.

It is an amenable number.

168618661 is a deficient number, since it is larger than the sum of its proper divisors (52551).

168618661 is an equidigital number, since it uses as much as digits as its factorization.

168618661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52550.

The product of its digits is 82944, while the sum is 43.

The square root of 168618661 is about 12985.3248322866. The cubic root of 168618661 is about 552.4613225452.

The spelling of 168618661 in words is "one hundred sixty-eight million, six hundred eighteen thousand, six hundred sixty-one".