66510491 has 2 divisors, whose sum is σ = 66510492. Its totient is φ = 66510490.

The previous prime is 66510467. The next prime is 66510529. The reversal of 66510491 is 19401566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66510491 - 2¹⁰ = 66509467 is a prime.

It is a super-2 number, since 2×66510491² = 8847290826122162, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66510401) 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, 33255245 + 33255246.

It is an arithmetic number, because the mean of its divisors is an integer number (33255246).

Almost surely, 2^66510491 is an apocalyptic number.

66510491 is a deficient number, since it is larger than the sum of its proper divisors (1).

66510491 is an equidigital number, since it uses as much as digits as its factorization.

66510491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 66510491 is about 8155.3964342636. The cubic root of 66510491 is about 405.1632548154.

The spelling of 66510491 in words is "sixty-six million, five hundred ten thousand, four hundred ninety-one".