66540213 has 6 divisors (see below), whose sum is σ = 96113654. Its totient is φ = 44360136.

The previous prime is 66540209. The next prime is 66540233. The reversal of 66540213 is 31204566.

66540213 is a `hidden beast` number, since 6 + 654 + 0 + 2 + 1 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 54199044 + 12341169 = 7362^2 + 3513^2 .

It is not a de Polignac number, because 66540213 - 2² = 66540209 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 (66540233) 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 5 ways as a sum of consecutive naturals, for example, 3696670 + ... + 3696687.

Almost surely, 2^66540213 is an apocalyptic number.

It is an amenable number.

66540213 is a deficient number, since it is larger than the sum of its proper divisors (29573441).

66540213 is a wasteful number, since it uses less digits than its factorization.

66540213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7393363 (or 7393360 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 66540213 is about 8157.2184597447. The cubic root of 66540213 is about 405.2235985232.

Adding to 66540213 its reverse (31204566), we get a palindrome (97744779).

The spelling of 66540213 in words is "sixty-six million, five hundred forty thousand, two hundred thirteen".