2021664 has 24 divisors (see below), whose sum is σ = 5307120. Its totient is φ = 673856.

The previous prime is 2021659. The next prime is 2021671. The reversal of 2021664 is 4661202.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

It is a nialpdrome in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 2021664.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10434 + ... + 10625.

It is an arithmetic number, because the mean of its divisors is an integer number (221130).

2^2021664 is an apocalyptic number.

2021664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

2021664 is an abundant number, since it is smaller than the sum of its proper divisors (3285456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2021664 is a wasteful number, since it uses less digits than its factorization.

2021664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21072 (or 21064 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 2021664 is about 1421.8523130058. The cubic root of 2021664 is about 126.4453877487.

Adding to 2021664 its reverse (4661202), we get a palindrome (6682866).

The spelling of 2021664 in words is "two million, twenty-one thousand, six hundred sixty-four".