1721606380 has 72 divisors (see below), whose sum is σ = 3927791952. Its totient is φ = 633574656.

The previous prime is 1721606357. The next prime is 1721606389. The reversal of 1721606380 is 836061271.

It is a super-3 number, since 3×1721606380³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1721606389) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1341219 + ... + 1342501.

It is an arithmetic number, because the mean of its divisors is an integer number (54552666).

Almost surely, 2^1721606380 is an apocalyptic number.

1721606380 is a gapful number since it is divisible by the number (10) 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 1721606380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1963895976).

1721606380 is an abundant number, since it is smaller than the sum of its proper divisors (2206185572).

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

1721606380 is a wasteful number, since it uses less digits than its factorization.

1721606380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1715 (or 1700 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 1721606380 is about 41492.2448175560. The cubic root of 1721606380 is about 1198.5181662642.

The spelling of 1721606380 in words is "one billion, seven hundred twenty-one million, six hundred six thousand, three hundred eighty".