721520739684 has 216 divisors, whose sum is σ = 1994766166848. Its totient is φ = 219692528640.

The previous prime is 721520739679. The next prime is 721520739697. The reversal of 721520739684 is 486937025127.

It is a happy number.

721520739684 is a `hidden beast` number, since 7 + 2 + 1 + 520 + 7 + 39 + 6 + 84 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 721520739684.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 170529849 + ... + 170534079.

It is a 1-persistent number, because it is pandigital, but 2⋅721520739684 = 1443041479368 is not.

Almost surely, 2^721520739684 is an apocalyptic number.

721520739684 is a gapful number since it is divisible by the number (74) 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 721520739684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (997383083424).

721520739684 is an abundant number, since it is smaller than the sum of its proper divisors (1273245427164).

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

721520739684 is a wasteful number, since it uses less digits than its factorization.

721520739684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4755 (or 4733 counting only the distinct ones).

The product of its (nonzero) digits is 5080320, while the sum is 54.

The spelling of 721520739684 in words is "seven hundred twenty-one billion, five hundred twenty million, seven hundred thirty-nine thousand, six hundred eighty-four".