66572323621 has 4 divisors (see below), whose sum is σ = 66591584332. Its totient is φ = 66553062912.

The previous prime is 66572323613. The next prime is 66572323679. The reversal of 66572323621 is 12632327566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10694455396 + 55877868225 = 103414^2 + 236385^2 .

It is a cyclic number.

It is not a de Polignac number, because 66572323621 - 2³ = 66572323613 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 (66572323691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9625170 + ... + 9632083.

It is an arithmetic number, because the mean of its divisors is an integer number (16647896083).

Almost surely, 2^66572323621 is an apocalyptic number.

It is an amenable number.

66572323621 is a deficient number, since it is larger than the sum of its proper divisors (19260711).

66572323621 is a wasteful number, since it uses less digits than its factorization.

66572323621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19260710.

The product of its digits is 544320, while the sum is 43.

The spelling of 66572323621 in words is "sixty-six billion, five hundred seventy-two million, three hundred twenty-three thousand, six hundred twenty-one".