1721139840 has 896 divisors, whose sum is σ = 7705912320. Its totient is φ = 358318080.

The previous prime is 1721139817. The next prime is 1721139851. The reversal of 1721139840 is 489311271.

It is a happy number.

1721139840 is a `hidden beast` number, since 17 + 211 + 398 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (896).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1721139795 and 1721139804.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 55520625 + ... + 55520655.

Almost surely, 2^1721139840 is an apocalyptic number.

1721139840 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 1721139840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3852956160).

1721139840 is an abundant number, since it is smaller than the sum of its proper divisors (5984772480).

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

1721139840 is an equidigital number, since it uses as much as digits as its factorization.

1721139840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 1721139840 is about 41486.6224221736. The cubic root of 1721139840 is about 1198.4098938995.

The spelling of 1721139840 in words is "one billion, seven hundred twenty-one million, one hundred thirty-nine thousand, eight hundred forty".