66213505 has 4 divisors (see below), whose sum is σ = 79456212. Its totient is φ = 52970800.

The previous prime is 66213503. The next prime is 66213509. The reversal of 66213505 is 50531266.

66213505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 41770369 + 24443136 = 6463^2 + 4944^2 .

It is not a de Polignac number, because 66213505 - 2¹ = 66213503 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66213503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6621346 + ... + 6621355.

It is an arithmetic number, because the mean of its divisors is an integer number (19864053).

Almost surely, 2^66213505 is an apocalyptic number.

It is an amenable number.

66213505 is a deficient number, since it is larger than the sum of its proper divisors (13242707).

66213505 is a wasteful number, since it uses less digits than its factorization.

66213505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13242706.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 66213505 is about 8137.1681191923. The cubic root of 66213505 is about 404.5593031875.

The spelling of 66213505 in words is "sixty-six million, two hundred thirteen thousand, five hundred five".