66147306821 has 4 divisors (see below), whose sum is σ = 68281090944. Its totient is φ = 64013522700.

The previous prime is 66147306769. The next prime is 66147306847. The reversal of 66147306821 is 12860374166.

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 66147306821 - 2¹⁴ = 66147290437 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 (66147306871) 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, 1066892015 + ... + 1066892076.

It is an arithmetic number, because the mean of its divisors is an integer number (17070272736).

Almost surely, 2^66147306821 is an apocalyptic number.

It is an amenable number.

66147306821 is a deficient number, since it is larger than the sum of its proper divisors (2133784123).

66147306821 is a wasteful number, since it uses less digits than its factorization.

66147306821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2133784122.

The product of its (nonzero) digits is 290304, while the sum is 44.

The spelling of 66147306821 in words is "sixty-six billion, one hundred forty-seven million, three hundred six thousand, eight hundred twenty-one".