6645778 has 4 divisors (see below), whose sum is σ = 9968670. Its totient is φ = 3322888.

The previous prime is 6645757. The next prime is 6645787. The reversal of 6645778 is 8775466.

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., 6466849 + 178929 = 2543^2 + 423^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1661443 + ... + 1661446.

Almost surely, 2^6645778 is an apocalyptic number.

6645778 is a deficient number, since it is larger than the sum of its proper divisors (3322892).

6645778 is a wasteful number, since it uses less digits than its factorization.

6645778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3322891.

The product of its digits is 282240, while the sum is 43.

The square root of 6645778 is about 2577.9406509848. The cubic root of 6645778 is about 188.0104302347.

The spelling of 6645778 in words is "six million, six hundred forty-five thousand, seven hundred seventy-eight".