66213826561 has 4 divisors (see below), whose sum is σ = 66219362352. Its totient is φ = 66208290772.

The previous prime is 66213826517. The next prime is 66213826577. The reversal of 66213826561 is 16562831266.

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 66213826561 - 2¹⁹ = 66213302273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66213826961) 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, 2749915 + ... + 2773888.

It is an arithmetic number, because the mean of its divisors is an integer number (16554840588).

Almost surely, 2^66213826561 is an apocalyptic number.

It is an amenable number.

66213826561 is a deficient number, since it is larger than the sum of its proper divisors (5535791).

66213826561 is a wasteful number, since it uses less digits than its factorization.

66213826561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5535790.

The product of its digits is 622080, while the sum is 46.

The spelling of 66213826561 in words is "sixty-six billion, two hundred thirteen million, eight hundred twenty-six thousand, five hundred sixty-one".