1721939856 has 160 divisors (see below), whose sum is σ = 5492981760. Its totient is φ = 452639232.

The previous prime is 1721939833. The next prime is 1721939861. The reversal of 1721939856 is 6589391271.

It is a junction number, because it is equal to n+sod(n) for n = 1721939799 and 1721939808.

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, 2091861 + ... + 2092683.

It is an arithmetic number, because the mean of its divisors is an integer number (34331136).

Almost surely, 2^1721939856 is an apocalyptic number.

1721939856 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 1721939856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2746490880).

1721939856 is an abundant number, since it is smaller than the sum of its proper divisors (3771041904).

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

1721939856 is a wasteful number, since it uses less digits than its factorization.

1721939856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333 (or 1327 counting only the distinct ones).

The product of its digits is 816480, while the sum is 51.

The square root of 1721939856 is about 41496.2631570603. The cubic root of 1721939856 is about 1198.5955457871.

It can be divided in two parts, 17219 and 39856, that added together give a palindrome (57075).

The spelling of 1721939856 in words is "one billion, seven hundred twenty-one million, nine hundred thirty-nine thousand, eight hundred fifty-six".