2218921 has 4 divisors (see below), whose sum is σ = 2230612. Its totient is φ = 2207232.

The previous prime is 2218907. The next prime is 2218933. The reversal of 2218921 is 1298122.

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 921600 + 1297321 = 960^2 + 1139^2 .

It is a cyclic number.

It is not a de Polignac number, because 2218921 - 2¹¹ = 2216873 is a prime.

It is a super-2 number, since 2×2218921² = 9847220808482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2218901) 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, 5556 + ... + 5941.

It is an arithmetic number, because the mean of its divisors is an integer number (557653).

2^2218921 is an apocalyptic number.

It is an amenable number.

2218921 is a deficient number, since it is larger than the sum of its proper divisors (11691).

2218921 is a wasteful number, since it uses less digits than its factorization.

2218921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11690.

The product of its digits is 576, while the sum is 25.

The square root of 2218921 is about 1489.6043098756. The cubic root of 2218921 is about 130.4309367739.

The spelling of 2218921 in words is "two million, two hundred eighteen thousand, nine hundred twenty-one".