2172221701721 has 4 divisors (see below), whose sum is σ = 2176933679844. Its totient is φ = 2167509723600.

The previous prime is 2172221701673. The next prime is 2172221701729. The reversal of 2172221701721 is 1271071222712.

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 937091761225 + 1235129940496 = 968035^2 + 1111364^2 .

It is a cyclic number.

It is not a de Polignac number, because 2172221701721 - 2²⁶ = 2172154592857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2172221701729) 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, 2355988370 + ... + 2355989291.

It is an arithmetic number, because the mean of its divisors is an integer number (544233419961).

Almost surely, 2^{2172221701721} is an apocalyptic number.

It is an amenable number.

2172221701721 is a deficient number, since it is larger than the sum of its proper divisors (4711978123).

2172221701721 is an equidigital number, since it uses as much as digits as its factorization.

2172221701721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4711978122.

The product of its (nonzero) digits is 10976, while the sum is 35.

The spelling of 2172221701721 in words is "two trillion, one hundred seventy-two billion, two hundred twenty-one million, seven hundred one thousand, seven hundred twenty-one".