66600581 has 2 divisors, whose sum is σ = 66600582. Its totient is φ = 66600580.

The previous prime is 66600563. The next prime is 66600587. The reversal of 66600581 is 18500666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51351556 + 15249025 = 7166^2 + 3905^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66600581 is a prime.

It is a super-2 number, since 2×66600581² = 8871274779075122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66600587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33300290 + 33300291.

It is an arithmetic number, because the mean of its divisors is an integer number (33300291).

Almost surely, 2^66600581 is an apocalyptic number.

It is an amenable number.

66600581 is a deficient number, since it is larger than the sum of its proper divisors (1).

66600581 is an equidigital number, since it uses as much as digits as its factorization.

66600581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 66600581 is about 8160.9179018049. The cubic root of 66600581 is about 405.3461066178.

The spelling of 66600581 in words is "sixty-six million, six hundred thousand, five hundred eighty-one".