2021643 has 24 divisors (see below), whose sum is σ = 3236688. Its totient is φ = 1207872.

The previous prime is 2021639. The next prime is 2021647. The reversal of 2021643 is 3461202.

It is a happy number.

2021643 is a `hidden beast` number, since 2 + 0 + 21 + 643 = 666.

It is an interprime number because it is at equal distance from previous prime (2021639) and next prime (2021647).

It is not a de Polignac number, because 2021643 - 2² = 2021639 is a prime.

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

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4096 + ... + 4562.

It is an arithmetic number, because the mean of its divisors is an integer number (134862).

2^2021643 is an apocalyptic number.

2021643 is a deficient number, since it is larger than the sum of its proper divisors (1215045).

2021643 is a wasteful number, since it uses less digits than its factorization.

2021643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523 (or 520 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 2021643 is about 1421.8449282534. The cubic root of 2021643 is about 126.4449499308. Note that the first 3 decimals are identical.

Adding to 2021643 its reverse (3461202), we get a palindrome (5482845).

The spelling of 2021643 in words is "two million, twenty-one thousand, six hundred forty-three".