2666520221 has 4 divisors (see below), whose sum is σ = 2667864192. Its totient is φ = 2665176252.

The previous prime is 2666520209. The next prime is 2666520253. The reversal of 2666520221 is 1220256662.

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 2666520221 - 2¹⁴ = 2666503837 is a prime.

It is a super-2 number, since 2×2666520221² = 14220660178003777682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2666520721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 669005 + ... + 672978.

It is an arithmetic number, because the mean of its divisors is an integer number (666966048).

Almost surely, 2^2666520221 is an apocalyptic number.

It is an amenable number.

2666520221 is a deficient number, since it is larger than the sum of its proper divisors (1343971).

2666520221 is a wasteful number, since it uses less digits than its factorization.

2666520221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343970.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 2666520221 is about 51638.3599758939. The cubic root of 2666520221 is about 1386.6971632981.

Adding to 2666520221 its reverse (1220256662), we get a palindrome (3886776883).

The spelling of 2666520221 in words is "two billion, six hundred sixty-six million, five hundred twenty thousand, two hundred twenty-one".