2666218521 has 4 divisors (see below), whose sum is σ = 3554958032. Its totient is φ = 1777479012.

The previous prime is 2666218481. The next prime is 2666218523. The reversal of 2666218521 is 1258126662.

2666218521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 2666218521 - 2⁷ = 2666218393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2666218521.

It is not an unprimeable number, because it can be changed into a prime (2666218523) 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, 444369751 + ... + 444369756.

It is an arithmetic number, because the mean of its divisors is an integer number (888739508).

Almost surely, 2^2666218521 is an apocalyptic number.

It is an amenable number.

2666218521 is a deficient number, since it is larger than the sum of its proper divisors (888739511).

2666218521 is an equidigital number, since it uses as much as digits as its factorization.

2666218521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888739510.

The product of its digits is 69120, while the sum is 39.

The square root of 2666218521 is about 51635.4386153541. The cubic root of 2666218521 is about 1386.6448626366.

The spelling of 2666218521 in words is "two billion, six hundred sixty-six million, two hundred eighteen thousand, five hundred twenty-one".