66511643 has 6 divisors (see below), whose sum is σ = 73107972. Its totient is φ = 60465020.

The previous prime is 66511597. The next prime is 66511649. The reversal of 66511643 is 34611566.

It is not a de Polignac number, because 66511643 - 2⁸ = 66511387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66511649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 274721 + ... + 274962.

It is an arithmetic number, because the mean of its divisors is an integer number (12184662).

Almost surely, 2^66511643 is an apocalyptic number.

66511643 is a deficient number, since it is larger than the sum of its proper divisors (6596329).

66511643 is a wasteful number, since it uses less digits than its factorization.

66511643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549705 (or 549694 counting only the distinct ones).

The product of its digits is 12960, while the sum is 32.

The square root of 66511643 is about 8155.4670620388. The cubic root of 66511643 is about 405.1655940222.

The spelling of 66511643 in words is "sixty-six million, five hundred eleven thousand, six hundred forty-three".