66215009 has 4 divisors (see below), whose sum is σ = 75674304. Its totient is φ = 56755716.

The previous prime is 66215003. The next prime is 66215011. The reversal of 66215009 is 90051266.

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 66215009 - 2¹² = 66210913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66215003) 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, 4729637 + ... + 4729650.

It is an arithmetic number, because the mean of its divisors is an integer number (18918576).

Almost surely, 2^66215009 is an apocalyptic number.

It is an amenable number.

66215009 is a deficient number, since it is larger than the sum of its proper divisors (9459295).

66215009 is an equidigital number, since it uses as much as digits as its factorization.

66215009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9459294.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 66215009 is about 8137.2605341110. The cubic root of 66215009 is about 404.5623662715.

The spelling of 66215009 in words is "sixty-six million, two hundred fifteen thousand, nine".