6440906 has 4 divisors (see below), whose sum is σ = 9661362. Its totient is φ = 3220452.

The previous prime is 6440893. The next prime is 6440933. The reversal of 6440906 is 6090446.

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., 4774225 + 1666681 = 2185^2 + 1291^2 .

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, 1610225 + ... + 1610228.

Almost surely, 2^6440906 is an apocalyptic number.

6440906 is a deficient number, since it is larger than the sum of its proper divisors (3220456).

6440906 is a wasteful number, since it uses less digits than its factorization.

6440906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3220455.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 6440906 is about 2537.8940088191. The cubic root of 6440906 is about 186.0582736437.

The spelling of 6440906 in words is "six million, four hundred forty thousand, nine hundred six".