1722721728 has 224 divisors, whose sum is σ = 5742854656. Its totient is φ = 443584512.

The previous prime is 1722721711. The next prime is 1722721757. The reversal of 1722721728 is 8271272271.

It is a tau number, because it is divible by the number of its divisors (224).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 750150 + ... + 752442.

It is an arithmetic number, because the mean of its divisors is an integer number (25637744).

Almost surely, 2^1722721728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1722721728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2871427328).

1722721728 is an abundant number, since it is smaller than the sum of its proper divisors (4020132928).

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

1722721728 is a wasteful number, since it uses less digits than its factorization.

1722721728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2371 (or 2361 counting only the distinct ones).

The product of its digits is 43904, while the sum is 39.

The square root of 1722721728 is about 41505.6830807541. The cubic root of 1722721728 is about 1198.7769316211.

Adding to 1722721728 its reverse (8271272271), we get a palindrome (9993993999).

The spelling of 1722721728 in words is "one billion, seven hundred twenty-two million, seven hundred twenty-one thousand, seven hundred twenty-eight".