66685817 has 4 divisors (see below), whose sum is σ = 72748176. Its totient is φ = 60623460.

The previous prime is 66685813. The next prime is 66685823. The reversal of 66685817 is 71858666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66685817 - 2² = 66685813 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66685813) 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 3 ways as a sum of consecutive naturals, for example, 3031163 + ... + 3031184.

It is an arithmetic number, because the mean of its divisors is an integer number (18187044).

Almost surely, 2^66685817 is an apocalyptic number.

It is an amenable number.

66685817 is a deficient number, since it is larger than the sum of its proper divisors (6062359).

66685817 is a wasteful number, since it uses less digits than its factorization.

66685817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6062358.

The product of its digits is 483840, while the sum is 47.

The square root of 66685817 is about 8166.1384386992. The cubic root of 66685817 is about 405.5189547198.

The spelling of 66685817 in words is "sixty-six million, six hundred eighty-five thousand, eight hundred seventeen".