6668399 has 6 divisors (see below), whose sum is σ = 6854904. Its totient is φ = 6486840.

The previous prime is 6668381. The next prime is 6668419. The reversal of 6668399 is 9938666.

6668399 = 188² + 189² + ... + 298².

It is a de Polignac number, because none of the positive numbers 2^k-6668399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6668359) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1067 + ... + 3804.

It is an arithmetic number, because the mean of its divisors is an integer number (1142484).

Almost surely, 2^6668399 is an apocalyptic number.

6668399 is a deficient number, since it is larger than the sum of its proper divisors (186505).

6668399 is an equidigital number, since it uses as much as digits as its factorization.

6668399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4945 (or 4908 counting only the distinct ones).

The product of its digits is 419904, while the sum is 47.

The square root of 6668399 is about 2582.3243405893. The cubic root of 6668399 is about 188.2235062452.

The spelling of 6668399 in words is "six million, six hundred sixty-eight thousand, three hundred ninety-nine".