1721440 has 96 divisors (see below), whose sum is σ = 4898880. Its totient is φ = 559104.

The previous prime is 1721417. The next prime is 1721441. The reversal of 1721440 is 441271.

1721440 is a nontrivial binomial coefficient, being equal to C(1856, 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721441) 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 15 ways as a sum of consecutive naturals, for example, 32454 + ... + 32506.

It is an arithmetic number, because the mean of its divisors is an integer number (51030).

2^1721440 is an apocalyptic number.

1721440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1721440 is the 1855-th triangular number and also the 928-th hexagonal number.

1721440 is the 619-th centered nonagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2449440).

1721440 is an abundant number, since it is smaller than the sum of its proper divisors (3177440).

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

1721440 is a wasteful number, since it uses less digits than its factorization.

1721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 1721440 is about 1312.0365848558. The cubic root of 1721440 is about 119.8479555836.

The spelling of 1721440 in words is "one million, seven hundred twenty-one thousand, four hundred forty".