664466681 has 2 divisors, whose sum is σ = 664466682. Its totient is φ = 664466680.

The previous prime is 664466639. The next prime is 664466687. The reversal of 664466681 is 186664466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 562638400 + 101828281 = 23720^2 + 10091^2 .

It is a cyclic number.

It is not a de Polignac number, because 664466681 - 2¹⁰ = 664465657 is a prime.

It is a super-2 number, since 2×664466681² = 883031940318311522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (664466687) 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 as a sum of consecutive naturals, namely, 332233340 + 332233341.

It is an arithmetic number, because the mean of its divisors is an integer number (332233341).

Almost surely, 2^664466681 is an apocalyptic number.

It is an amenable number.

664466681 is a deficient number, since it is larger than the sum of its proper divisors (1).

664466681 is an equidigital number, since it uses as much as digits as its factorization.

664466681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 995328, while the sum is 47.

The square root of 664466681 is about 25777.2512304939. The cubic root of 664466681 is about 872.6184735250.

The spelling of 664466681 in words is "six hundred sixty-four million, four hundred sixty-six thousand, six hundred eighty-one".