6400666 has 4 divisors (see below), whose sum is σ = 9601002. Its totient is φ = 3200332.

The previous prime is 6400657. The next prime is 6400697. The reversal of 6400666 is 6660046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 5157441 + 1243225 = 2271^2 + 1115^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1600165 + ... + 1600168.

Almost surely, 2^6400666 is an apocalyptic number.

6400666 is a deficient number, since it is larger than the sum of its proper divisors (3200336).

6400666 is a wasteful number, since it uses less digits than its factorization.

6400666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3200335.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 6400666 is about 2529.9537545181. The cubic root of 6400666 is about 185.6699933256.

The spelling of 6400666 in words is "six million, four hundred thousand, six hundred sixty-six".