721968128 has 88 divisors (see below), whose sum is σ = 1685286912. Its totient is φ = 302690304.

The previous prime is 721968127. The next prime is 721968131. The reversal of 721968128 is 821869127.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721968127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 335825 + ... + 337967.

Almost surely, 2^721968128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721968128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (842643456).

721968128 is an abundant number, since it is smaller than the sum of its proper divisors (963318784).

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

721968128 is a wasteful number, since it uses less digits than its factorization.

721968128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2217 (or 2199 counting only the distinct ones).

The product of its digits is 96768, while the sum is 44.

The square root of 721968128 is about 26869.4646020348. The cubic root of 721968128 is about 897.0968709633.

Subtracting 721968128 from its reverse (821869127), we obtain a palindrome (99900999).

It can be divided in two parts, 72 and 1968128, that multiplied together give a square (141705216 = 11904²).

The spelling of 721968128 in words is "seven hundred twenty-one million, nine hundred sixty-eight thousand, one hundred twenty-eight".