2209821 has 4 divisors (see below), whose sum is σ = 2946432. Its totient is φ = 1473212.

The previous prime is 2209811. The next prime is 2209841. The reversal of 2209821 is 1289022.

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 2209821 - 2⁵ = 2209789 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 2209791 and 2209800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2209811) 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, 368301 + ... + 368306.

It is an arithmetic number, because the mean of its divisors is an integer number (736608).

2^2209821 is an apocalyptic number.

It is an amenable number.

2209821 is a deficient number, since it is larger than the sum of its proper divisors (736611).

2209821 is an equidigital number, since it uses as much as digits as its factorization.

2209821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736610.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 2209821 is about 1486.5466692977. The cubic root of 2209821 is about 130.2523893643.

The spelling of 2209821 in words is "two million, two hundred nine thousand, eight hundred twenty-one".