2216721 has 16 divisors (see below), whose sum is σ = 3217536. Its totient is φ = 1349376.

The previous prime is 2216701. The next prime is 2216729. The reversal of 2216721 is 1276122.

It is not a de Polignac number, because 2216721 - 2⁶ = 2216657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2216729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4156 + ... + 4658.

It is an arithmetic number, because the mean of its divisors is an integer number (201096).

2^2216721 is an apocalyptic number.

It is an amenable number.

2216721 is a deficient number, since it is larger than the sum of its proper divisors (1000815).

2216721 is a wasteful number, since it uses less digits than its factorization.

2216721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 632.

The product of its digits is 336, while the sum is 21.

The square root of 2216721 is about 1488.8656756068. The cubic root of 2216721 is about 130.3878162742.

The spelling of 2216721 in words is "two million, two hundred sixteen thousand, seven hundred twenty-one".