2217921 has 4 divisors (see below), whose sum is σ = 2957232. Its totient is φ = 1478612.

The previous prime is 2217911. The next prime is 2217947. The reversal of 2217921 is 1297122.

2217921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 2217921 - 2⁶ = 2217857 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 2217891 and 2217900.

It is not an unprimeable number, because it can be changed into a prime (2217911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 369651 + ... + 369656.

It is an arithmetic number, because the mean of its divisors is an integer number (739308).

2^2217921 is an apocalyptic number.

It is an amenable number.

2217921 is a deficient number, since it is larger than the sum of its proper divisors (739311).

2217921 is an equidigital number, since it uses as much as digits as its factorization.

2217921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 739310.

The product of its digits is 504, while the sum is 24.

The square root of 2217921 is about 1489.2686124403. The cubic root of 2217921 is about 130.4113400817.

The spelling of 2217921 in words is "two million, two hundred seventeen thousand, nine hundred twenty-one".