1665667 has 4 divisors (see below), whose sum is σ = 1670400. Its totient is φ = 1660936.

The previous prime is 1665659. The next prime is 1665679. The reversal of 1665667 is 7665661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7665661 = 263 ⋅29147.

It is a cyclic number.

It is not a de Polignac number, because 1665667 - 2³ = 1665659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665647) 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, 1792 + ... + 2557.

It is an arithmetic number, because the mean of its divisors is an integer number (417600).

2^1665667 is an apocalyptic number.

1665667 is a deficient number, since it is larger than the sum of its proper divisors (4733).

1665667 is an equidigital number, since it uses as much as digits as its factorization.

1665667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4732.

The product of its digits is 45360, while the sum is 37.

The square root of 1665667 is about 1290.6072214272. The cubic root of 1665667 is about 118.5394006909.

It can be divided in two parts, 1665 and 667, that added together give a palindrome (2332).

The spelling of 1665667 in words is "one million, six hundred sixty-five thousand, six hundred sixty-seven".