66856605 has 16 divisors (see below), whose sum is σ = 107075520. Its totient is φ = 35621888.

The previous prime is 66856577. The next prime is 66856633. The reversal of 66856605 is 50665866.

It is an interprime number because it is at equal distance from previous prime (66856577) and next prime (66856633).

It is a cyclic number.

It is not a de Polignac number, because 66856605 - 2⁹ = 66856093 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22909 + ... + 25661.

It is an arithmetic number, because the mean of its divisors is an integer number (6692220).

Almost surely, 2^66856605 is an apocalyptic number.

It is an amenable number.

66856605 is a deficient number, since it is larger than the sum of its proper divisors (40218915).

66856605 is a wasteful number, since it uses less digits than its factorization.

66856605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4380.

The product of its (nonzero) digits is 259200, while the sum is 42.

The square root of 66856605 is about 8176.5888364281. The cubic root of 66856605 is about 405.8648490110.

The spelling of 66856605 in words is "sixty-six million, eight hundred fifty-six thousand, six hundred five".