66559815 has 48 divisors (see below), whose sum is σ = 137599488. Its totient is φ = 29101248.

The previous prime is 66559813. The next prime is 66559837. The reversal of 66559815 is 51895566.

It is a happy number.

It is not a de Polignac number, because 66559815 - 2¹ = 66559813 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66559813) 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 47 ways as a sum of consecutive naturals, for example, 2652 + ... + 11838.

It is an arithmetic number, because the mean of its divisors is an integer number (2866656).

Almost surely, 2^66559815 is an apocalyptic number.

66559815 is an abundant number, since it is smaller than the sum of its proper divisors (71039673).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66559815 is a wasteful number, since it uses less digits than its factorization.

66559815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9228 (or 9225 counting only the distinct ones).

The product of its digits is 324000, while the sum is 45.

The square root of 66559815 is about 8158.4198837765. The cubic root of 66559815 is about 405.2633860580.

The spelling of 66559815 in words is "sixty-six million, five hundred fifty-nine thousand, eight hundred fifteen".