2217115721721 has 32 divisors (see below), whose sum is σ = 3270247907328. Its totient is φ = 1331227465920.

The previous prime is 2217115721701. The next prime is 2217115721731. The reversal of 2217115721721 is 1271275117122.

It is a happy number.

2217115721721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2217115721721 - 2⁶ = 2217115721657 is a prime.

It is a super-2 number, since 2×2217115721721² (a number of 25 digits) contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2217115721721.

It is not an unprimeable number, because it can be changed into a prime (2217115721701) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13927881 + ... + 14086166.

It is an arithmetic number, because the mean of its divisors is an integer number (102195247104).

Almost surely, 2^{2217115721721} is an apocalyptic number.

It is an amenable number.

2217115721721 is a deficient number, since it is larger than the sum of its proper divisors (1053132185607).

2217115721721 is a wasteful number, since it uses less digits than its factorization.

2217115721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28014141.

The product of its digits is 27440, while the sum is 39.

The spelling of 2217115721721 in words is "two trillion, two hundred seventeen billion, one hundred fifteen million, seven hundred twenty-one thousand, seven hundred twenty-one".