1666618 has 4 divisors (see below), whose sum is σ = 2499930. Its totient is φ = 833308.

The previous prime is 1666607. The next prime is 1666619. The reversal of 1666618 is 8166661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8166661 = 29 ⋅281609.

It can be written as a sum of positive squares in only one way, i.e., 1194649 + 471969 = 1093^2 + 687^2 .

It is not an unprimeable number, because it can be changed into a prime (1666619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416653 + ... + 416656.

2^1666618 is an apocalyptic number.

1666618 is a deficient number, since it is larger than the sum of its proper divisors (833312).

1666618 is an equidigital number, since it uses as much as digits as its factorization.

1666618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833311.

The product of its digits is 10368, while the sum is 34.

The square root of 1666618 is about 1290.9756000793. The cubic root of 1666618 is about 118.5619561242.

The spelling of 1666618 in words is "one million, six hundred sixty-six thousand, six hundred eighteen".