664878397 has 2 divisors, whose sum is σ = 664878398. Its totient is φ = 664878396.

The previous prime is 664878377. The next prime is 664878407. The reversal of 664878397 is 793878466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 569347321 + 95531076 = 23861^2 + 9774^2 .

It is a cyclic number.

It is not a de Polignac number, because 664878397 - 2¹⁹ = 664354109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664878337) 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, 332439198 + 332439199.

It is an arithmetic number, because the mean of its divisors is an integer number (332439199).

Almost surely, 2^664878397 is an apocalyptic number.

It is an amenable number.

664878397 is a deficient number, since it is larger than the sum of its proper divisors (1).

664878397 is an equidigital number, since it uses as much as digits as its factorization.

664878397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12192768, while the sum is 58.

The square root of 664878397 is about 25785.2360276186. The cubic root of 664878397 is about 872.7986665628.

The spelling of 664878397 in words is "six hundred sixty-four million, eight hundred seventy-eight thousand, three hundred ninety-seven".