66040691 has 4 divisors (see below), whose sum is σ = 66945432. Its totient is φ = 65135952.

The previous prime is 66040669. The next prime is 66040717. The reversal of 66040691 is 19604066.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66040691 - 2¹⁰ = 66039667 is a prime.

It is a super-4 number, since 4×66040691⁴ (a number of 32 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66046691) 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 in 3 ways as a sum of consecutive naturals, for example, 452261 + ... + 452406.

It is an arithmetic number, because the mean of its divisors is an integer number (16736358).

Almost surely, 2^66040691 is an apocalyptic number.

66040691 is a deficient number, since it is larger than the sum of its proper divisors (904741).

66040691 is an equidigital number, since it uses as much as digits as its factorization.

66040691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 904740.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 66040691 is about 8126.5423766815. The cubic root of 66040691 is about 404.2070365646.

The spelling of 66040691 in words is "sixty-six million, forty thousand, six hundred ninety-one".