66646791 has 6 divisors (see below), whose sum is σ = 96267600. Its totient is φ = 44431188.

The previous prime is 66646787. The next prime is 66646819. The reversal of 66646791 is 19764666.

It is a happy number.

It is not a de Polignac number, because 66646791 - 2² = 66646787 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66646291) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3702591 + ... + 3702608.

It is an arithmetic number, because the mean of its divisors is an integer number (16044600).

Almost surely, 2^66646791 is an apocalyptic number.

66646791 is a deficient number, since it is larger than the sum of its proper divisors (29620809).

66646791 is a wasteful number, since it uses less digits than its factorization.

66646791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7405205 (or 7405202 counting only the distinct ones).

The product of its digits is 326592, while the sum is 45.

The square root of 66646791 is about 8163.7485875056. The cubic root of 66646791 is about 405.4398330932.

The spelling of 66646791 in words is "sixty-six million, six hundred forty-six thousand, seven hundred ninety-one".