2175220721 has 4 divisors (see below), whose sum is σ = 2175813744. Its totient is φ = 2174627700.

The previous prime is 2175220717. The next prime is 2175220781. The reversal of 2175220721 is 1270225712.

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 2175220721 - 2² = 2175220717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2175220781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290975 + ... + 298356.

It is an arithmetic number, because the mean of its divisors is an integer number (543953436).

Almost surely, 2^2175220721 is an apocalyptic number.

It is an amenable number.

2175220721 is a deficient number, since it is larger than the sum of its proper divisors (593023).

2175220721 is an equidigital number, since it uses as much as digits as its factorization.

2175220721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593022.

The product of its (nonzero) digits is 3920, while the sum is 29.

The square root of 2175220721 is about 46639.2615829196. The cubic root of 2175220721 is about 1295.6900107761.

The spelling of 2175220721 in words is "two billion, one hundred seventy-five million, two hundred twenty thousand, seven hundred twenty-one".