1721868840 has 136 divisors (see below), whose sum is σ = 5811307290. Its totient is φ = 459165024.

The previous prime is 1721868839. The next prime is 1721868877. The reversal of 1721868840 is 488681271.

It can be written as a sum of positive squares in only one way, i.e., 1549681956 + 172186884 = 39366^2 + 13122^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a nialpdrome in base 3 and base 9.

It is a zygodrome in base 3 and base 9.

It is an unprimeable number.

It is a polite number, since it can be written in 33 ways as a sum of consecutive naturals, for example, 344373766 + ... + 344373770.

Almost surely, 2^1721868840 is an apocalyptic number.

1721868840 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 1721868840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2905653645).

1721868840 is an abundant number, since it is smaller than the sum of its proper divisors (4089438450).

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

1721868840 is an frugal number, since it uses more digits than its factorization.

1721868840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59 (or 10 counting only the distinct ones).

The product of its (nonzero) digits is 172032, while the sum is 45.

The square root of 1721868840 is about 41495.4074567295. The cubic root of 1721868840 is about 1198.5790681246.

The spelling of 1721868840 in words is "one billion, seven hundred twenty-one million, eight hundred sixty-eight thousand, eight hundred forty".