66221115521 has 4 divisors (see below), whose sum is σ = 72241216944. Its totient is φ = 60201014100.

The previous prime is 66221115497. The next prime is 66221115557. The reversal of 66221115521 is 12551112266.

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 66221115521 - 2¹⁰ = 66221114497 is a prime.

It is a super-2 number, since 2×66221115521² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66221112521) 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, 3010050695 + ... + 3010050716.

It is an arithmetic number, because the mean of its divisors is an integer number (18060304236).

Almost surely, 2^66221115521 is an apocalyptic number.

It is an amenable number.

66221115521 is a deficient number, since it is larger than the sum of its proper divisors (6020101423).

66221115521 is a wasteful number, since it uses less digits than its factorization.

66221115521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6020101422.

The product of its digits is 7200, while the sum is 32.

Adding to 66221115521 its reverse (12551112266), we get a palindrome (78772227787).

The spelling of 66221115521 in words is "sixty-six billion, two hundred twenty-one million, one hundred fifteen thousand, five hundred twenty-one".