6688778 has 4 divisors (see below), whose sum is σ = 10033170. Its totient is φ = 3344388.

The previous prime is 6688757. The next prime is 6688783. The reversal of 6688778 is 8778866.

It is a happy number.

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., 6115729 + 573049 = 2473^2 + 757^2 .

It is a super-2 number, since 2×6688778² = 89479502266568, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1672193 + ... + 1672196.

Almost surely, 2^6688778 is an apocalyptic number.

6688778 is a deficient number, since it is larger than the sum of its proper divisors (3344392).

6688778 is a wasteful number, since it uses less digits than its factorization.

6688778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3344391.

The product of its digits is 903168, while the sum is 50.

The square root of 6688778 is about 2586.2671942396. The cubic root of 6688778 is about 188.4150517708.

The spelling of 6688778 in words is "six million, six hundred eighty-eight thousand, seven hundred seventy-eight".