1643664 has 60 divisors (see below), whose sum is σ = 4683728. Its totient is φ = 496320.

The previous prime is 1643659. The next prime is 1643669. The reversal of 1643664 is 4663461.

It is an interprime number because it is at equal distance from previous prime (1643659) and next prime (1643669).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1643669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5667 + ... + 5949.

2^1643664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2341864).

1643664 is an abundant number, since it is smaller than the sum of its proper divisors (3040064).

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

1643664 is a wasteful number, since it uses less digits than its factorization.

1643664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316 (or 299 counting only the distinct ones).

The product of its digits is 10368, while the sum is 30.

The square root of 1643664 is about 1282.0546010213. The cubic root of 1643664 is about 118.0151278125.

It can be divided in two parts, 164 and 3664, that added together give a triangular number (3828 = T₈₇).

The spelling of 1643664 in words is "one million, six hundred forty-three thousand, six hundred sixty-four".