1721616 has 80 divisors (see below), whose sum is σ = 4999680. Its totient is φ = 506880.

The previous prime is 1721593. The next prime is 1721633. The reversal of 1721616 is 6161271.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

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, 19300 + ... + 19388.

It is an arithmetic number, because the mean of its divisors is an integer number (62496).

2^1721616 is an apocalyptic number.

1721616 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 1721616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2499840).

1721616 is an abundant number, since it is smaller than the sum of its proper divisors (3278064).

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

1721616 is a wasteful number, since it uses less digits than its factorization.

1721616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144 (or 138 counting only the distinct ones).

The product of its digits is 504, while the sum is 24.

The square root of 1721616 is about 1312.1036544420. The cubic root of 1721616 is about 119.8520398622.

Adding to 1721616 its reverse (6161271), we get a palindrome (7882887).

The spelling of 1721616 in words is "one million, seven hundred twenty-one thousand, six hundred sixteen".