666678449 has 2 divisors, whose sum is σ = 666678450. Its totient is φ = 666678448.

The previous prime is 666678379. The next prime is 666678487. The reversal of 666678449 is 944876666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 652291600 + 14386849 = 25540^2 + 3793^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666678449 is a prime.

It is a super-2 number, since 2×666678449² = 888920308722091202, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 666678394 and 666678403.

It is not a weakly prime, because it can be changed into another prime (666678949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333339224 + 333339225.

It is an arithmetic number, because the mean of its divisors is an integer number (333339225).

Almost surely, 2^666678449 is an apocalyptic number.

It is an amenable number.

666678449 is a deficient number, since it is larger than the sum of its proper divisors (1).

666678449 is an equidigital number, since it uses as much as digits as its factorization.

666678449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10450944, while the sum is 56.

The square root of 666678449 is about 25820.1171376119. The cubic root of 666678449 is about 873.5856111141.

The spelling of 666678449 in words is "six hundred sixty-six million, six hundred seventy-eight thousand, four hundred forty-nine".