66398815 has 16 divisors (see below), whose sum is σ = 95021568. Its totient is φ = 43550496.

The previous prime is 66398747. The next prime is 66398819. The reversal of 66398815 is 51889366.

It is a cyclic number.

It is not a de Polignac number, because 66398815 - 2¹¹ = 66396767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66398819) 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 15 ways as a sum of consecutive naturals, for example, 40437 + ... + 42046.

It is an arithmetic number, because the mean of its divisors is an integer number (5938848).

Almost surely, 2^66398815 is an apocalyptic number.

66398815 is a deficient number, since it is larger than the sum of its proper divisors (28622753).

66398815 is a wasteful number, since it uses less digits than its factorization.

66398815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82518.

The product of its digits is 311040, while the sum is 46.

The square root of 66398815 is about 8148.5468029582. The cubic root of 66398815 is about 404.9363614890.

The spelling of 66398815 in words is "sixty-six million, three hundred ninety-eight thousand, eight hundred fifteen".