16665665 has 4 divisors (see below), whose sum is σ = 19998804. Its totient is φ = 13332528.

The previous prime is 16665643. The next prime is 16665673. The reversal of 16665665 is 56656661.

16665665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56656661 = 229 ⋅247409.

It can be written as a sum of positive squares in 2 ways, for example, as 10029889 + 6635776 = 3167^2 + 2576^2 .

It is a cyclic number.

It is not a de Polignac number, because 16665665 - 2⁶ = 16665601 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1666562 + ... + 1666571.

It is an arithmetic number, because the mean of its divisors is an integer number (4999701).

Almost surely, 2^16665665 is an apocalyptic number.

It is an amenable number.

16665665 is a deficient number, since it is larger than the sum of its proper divisors (3333139).

16665665 is an equidigital number, since it uses as much as digits as its factorization.

16665665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3333138.

The product of its digits is 194400, while the sum is 41.

The square root of 16665665 is about 4082.3602241840. The cubic root of 16665665 is about 255.4313601179.

It can be divided in two parts, 1 and 6665665, that added together give a palindrome (6665666).

The spelling of 16665665 in words is "sixteen million, six hundred sixty-five thousand, six hundred sixty-five".