2118721 has 4 divisors (see below), whose sum is σ = 2311344. Its totient is φ = 1926100.

The previous prime is 2118703. The next prime is 2118733. The reversal of 2118721 is 1278112.

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 not a de Polignac number, because 2118721 - 2⁵ = 2118689 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2118692 and 2118701.

It is not an unprimeable number, because it can be changed into a prime (2118751) 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, 96295 + ... + 96316.

It is an arithmetic number, because the mean of its divisors is an integer number (577836).

2^2118721 is an apocalyptic number.

It is an amenable number.

2118721 is a deficient number, since it is larger than the sum of its proper divisors (192623).

2118721 is a wasteful number, since it uses less digits than its factorization.

2118721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192622.

The product of its digits is 224, while the sum is 22.

The square root of 2118721 is about 1455.5827011888. The cubic root of 2118721 is about 128.4373265508.

The spelling of 2118721 in words is "two million, one hundred eighteen thousand, seven hundred twenty-one".