664784666 has 24 divisors (see below), whose sum is σ = 1249213140. Its totient is φ = 262991232.

The previous prime is 664784657. The next prime is 664784669. The reversal of 664784666 is 666487466.

It can be written as a sum of positive squares in 2 ways, for example, as 643890625 + 20894041 = 25375^2 + 4571^2 .

It is not an unprimeable number, because it can be changed into a prime (664784669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 259631 + ... + 262178.

Almost surely, 2^664784666 is an apocalyptic number.

664784666 is a deficient number, since it is larger than the sum of its proper divisors (584428474).

664784666 is a wasteful number, since it uses less digits than its factorization.

664784666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521838 (or 521831 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 53.

The square root of 664784666 is about 25783.4184312321. The cubic root of 664784666 is about 872.7576504729.

The spelling of 664784666 in words is "six hundred sixty-four million, seven hundred eighty-four thousand, six hundred sixty-six".