66213517 has 4 divisors (see below), whose sum is σ = 67335840. Its totient is φ = 65091196.

The previous prime is 66213509. The next prime is 66213523. The reversal of 66213517 is 71531266.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66213517 - 2³ = 66213509 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66213817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 561073 + ... + 561190.

It is an arithmetic number, because the mean of its divisors is an integer number (16833960).

Almost surely, 2^66213517 is an apocalyptic number.

It is an amenable number.

66213517 is a deficient number, since it is larger than the sum of its proper divisors (1122323).

66213517 is a wasteful number, since it uses less digits than its factorization.

66213517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1122322.

The product of its digits is 7560, while the sum is 31.

The square root of 66213517 is about 8137.1688565496. The cubic root of 66213517 is about 404.5593276271.

The spelling of 66213517 in words is "sixty-six million, two hundred thirteen thousand, five hundred seventeen".