1728640 has 64 divisors (see below), whose sum is σ = 4302360. Its totient is φ = 663552.

The previous prime is 1728593. The next prime is 1728659. The reversal of 1728640 is 468271.

1728640 = T₇₅ + T₇₆ + ... + T₂₂₀.

It can be written as a sum of positive squares in 4 ways, for example, as 1658944 + 69696 = 1288^2 + 264^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is a junction number, because it is equal to n+sod(n) for n = 1728599 and 1728608.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23644 + ... + 23716.

2^1728640 is an apocalyptic number.

1728640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1728640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2151180).

1728640 is an abundant number, since it is smaller than the sum of its proper divisors (2573720).

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

1728640 is an equidigital number, since it uses as much as digits as its factorization.

1728640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 1728640 is about 1314.7775477243. Note that the first 3 decimals coincide. The cubic root of 1728640 is about 120.0148129862.

The spelling of 1728640 in words is "one million, seven hundred twenty-eight thousand, six hundred forty".