66815 has 16 divisors (see below), whose sum is σ = 96768. Its totient is φ = 43296.

The previous prime is 66809. The next prime is 66821. The reversal of 66815 is 51866.

It is an interprime number because it is at equal distance from previous prime (66809) and next prime (66821).

It is a cyclic number.

It is not a de Polignac number, because 66815 - 2⁶ = 66751 is a prime.

It is a plaindrome in base 9.

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, 764 + ... + 846.

It is an arithmetic number, because the mean of its divisors is an integer number (6048).

2⁶⁶⁸¹⁵ is an apocalyptic number.

66815 is a deficient number, since it is larger than the sum of its proper divisors (29953).

66815 is a wasteful number, since it uses less digits than its factorization.

66815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118.

The product of its digits is 1440, while the sum is 26.

The square root of 66815 is about 258.4859764088. The cubic root of 66815 is about 40.5780641370.

The spelling of 66815 in words is "sixty-six thousand, eight hundred fifteen".