1721856 has 80 divisors (see below), whose sum is σ = 4910400. Its totient is φ = 534528.

The previous prime is 1721831. The next prime is 1721857. The reversal of 1721856 is 6581271.

It is a nialpdrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721857) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29155 + ... + 29213.

It is an arithmetic number, because the mean of its divisors is an integer number (61380).

2^1721856 is an apocalyptic number.

1721856 is a gapful number since it is divisible by the number (16) 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 1721856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2455200).

1721856 is an abundant number, since it is smaller than the sum of its proper divisors (3188544).

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

1721856 is an equidigital number, since it uses as much as digits as its factorization.

1721856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 83 counting only the distinct ones).

The product of its digits is 3360, while the sum is 30.

The square root of 1721856 is about 1312.1951074440. The cubic root of 1721856 is about 119.8576088844.

The spelling of 1721856 in words is "one million, seven hundred twenty-one thousand, eight hundred fifty-six".