2221821 has 12 divisors (see below), whose sum is σ = 3667872. Its totient is φ = 1269576.

The previous prime is 2221789. The next prime is 2221829. The reversal of 2221821 is 1281222.

It is a happy number.

It is not a de Polignac number, because 2221821 - 2⁵ = 2221789 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2221794 and 2221803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2221829) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17571 + ... + 17696.

It is an arithmetic number, because the mean of its divisors is an integer number (305656).

2^2221821 is an apocalyptic number.

2221821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2221821 is a deficient number, since it is larger than the sum of its proper divisors (1446051).

2221821 is a wasteful number, since it uses less digits than its factorization.

2221821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35280 (or 35277 counting only the distinct ones).

The product of its digits is 128, while the sum is 18.

The square root of 2221821 is about 1490.5774049005. The cubic root of 2221821 is about 130.4877339068.

The spelling of 2221821 in words is "two million, two hundred twenty-one thousand, eight hundred twenty-one".