6778661 has 2 divisors, whose sum is σ = 6778662. Its totient is φ = 6778660.

The previous prime is 6778643. The next prime is 6778691. The reversal of 6778661 is 1668776.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6002500 + 776161 = 2450^2 + 881^2 .

It is a cyclic number.

It is not a de Polignac number, because 6778661 - 2¹⁰ = 6777637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6778621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3389330 + 3389331.

It is an arithmetic number, because the mean of its divisors is an integer number (3389331).

Almost surely, 2^6778661 is an apocalyptic number.

It is an amenable number.

6778661 is a deficient number, since it is larger than the sum of its proper divisors (1).

6778661 is an equidigital number, since it uses as much as digits as its factorization.

6778661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 41.

The square root of 6778661 is about 2603.5861806362. The cubic root of 6778661 is about 189.2552656917.

The spelling of 6778661 in words is "six million, seven hundred seventy-eight thousand, six hundred sixty-one".