1643680 has 24 divisors (see below), whose sum is σ = 3883572. Its totient is φ = 657408.

The previous prime is 1643669. The next prime is 1643683. The reversal of 1643680 is 863461.

It can be written as a sum of positive squares in 2 ways, for example, as 1567504 + 76176 = 1252^2 + 276^2 .

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1643683) 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 3 ways as a sum of consecutive naturals, for example, 4977 + ... + 5296.

2^1643680 is an apocalyptic number.

1643680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1643680 is an abundant number, since it is smaller than the sum of its proper divisors (2239892).

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

1643680 is a wasteful number, since it uses less digits than its factorization.

1643680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10288 (or 10280 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 1643680 is about 1282.0608409900. The cubic root of 1643680 is about 118.0155107448.

It can be divided in two parts, 164 and 3680, that added together give a square (3844 = 62²).

The spelling of 1643680 in words is "one million, six hundred forty-three thousand, six hundred eighty".