2021644 has 6 divisors (see below), whose sum is σ = 3537884. Its totient is φ = 1010820.

The previous prime is 2021639. The next prime is 2021647. The reversal of 2021644 is 4461202.

It is not an unprimeable number, because it can be changed into a prime (2021647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 252702 + ... + 252709.

2^2021644 is an apocalyptic number.

It is an amenable number.

2021644 is a deficient number, since it is larger than the sum of its proper divisors (1516240).

2021644 is a wasteful number, since it uses less digits than its factorization.

2021644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505415 (or 505413 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 2021644 is about 1421.8452799092. The cubic root of 2021644 is about 126.4449707793. Note that the first 3 decimals are identical.

Adding to 2021644 its reverse (4461202), we get a palindrome (6482846).

The spelling of 2021644 in words is "two million, twenty-one thousand, six hundred forty-four".