2197821 has 8 divisors (see below), whose sum is σ = 2939680. Its totient is φ = 1460592.

The previous prime is 2197799. The next prime is 2197847. The reversal of 2197821 is 1287912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2197821 - 2⁷ = 2197693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2197021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 171 + ... + 2103.

It is an arithmetic number, because the mean of its divisors is an integer number (367460).

2^2197821 is an apocalyptic number.

It is an amenable number.

2197821 is a deficient number, since it is larger than the sum of its proper divisors (741859).

2197821 is a wasteful number, since it uses less digits than its factorization.

2197821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2315.

The product of its digits is 2016, while the sum is 30.

The square root of 2197821 is about 1482.5049746965. The cubic root of 2197821 is about 130.0161912772.

Subtracting from 2197821 its reverse (1287912), we obtain a palindrome (909909).

The spelling of 2197821 in words is "two million, one hundred ninety-seven thousand, eight hundred twenty-one".