664040081 has 2 divisors, whose sum is σ = 664040082. Its totient is φ = 664040080.

The previous prime is 664040011. The next prime is 664040087. The reversal of 664040081 is 180040466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 499969600 + 164070481 = 22360^2 + 12809^2 .

It is a cyclic number.

It is not a de Polignac number, because 664040081 - 2²² = 659845777 is a prime.

It is a super-2 number, since 2×664040081² = 881898458348973122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (664040087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332020040 + 332020041.

It is an arithmetic number, because the mean of its divisors is an integer number (332020041).

Almost surely, 2^664040081 is an apocalyptic number.

It is an amenable number.

664040081 is a deficient number, since it is larger than the sum of its proper divisors (1).

664040081 is an equidigital number, since it uses as much as digits as its factorization.

664040081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 664040081 is about 25768.9751639447. The cubic root of 664040081 is about 872.4316877686.

The spelling of 664040081 in words is "six hundred sixty-four million, forty thousand, eighty-one".