66530216517221 has 4 divisors (see below), whose sum is σ = 67945753038912. Its totient is φ = 65114679995532.

The previous prime is 66530216517203. The next prime is 66530216517223. The reversal of 66530216517221 is 12271561203566.

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 a de Polignac number, because none of the positive numbers 2^k-66530216517221 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47), and also a Moran number because the ratio is a prime number: 1415536521643 = 66530216517221 / (6 + 6 + 5 + 3 + 0 + 2 + 1 + 6 + 5 + 1 + 7 + 2 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66530216517223) 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, 707768260775 + ... + 707768260868.

It is an arithmetic number, because the mean of its divisors is an integer number (16986438259728).

Almost surely, 2^{66530216517221} is an apocalyptic number.

It is an amenable number.

66530216517221 is a deficient number, since it is larger than the sum of its proper divisors (1415536521691).

66530216517221 is a wasteful number, since it uses less digits than its factorization.

66530216517221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1415536521690.

The product of its (nonzero) digits is 907200, while the sum is 47.

The spelling of 66530216517221 in words is "sixty-six trillion, five hundred thirty billion, two hundred sixteen million, five hundred seventeen thousand, two hundred twenty-one".