721988128 has 12 divisors (see below), whose sum is σ = 1421414190. Its totient is φ = 360994048.

The previous prime is 721988117. The next prime is 721988149. The reversal of 721988128 is 821889127.

It can be written as a sum of positive squares in only one way, i.e., 459159184 + 262828944 = 21428^2 + 16212^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11281033 + ... + 11281096.

Almost surely, 2^721988128 is an apocalyptic number.

It is an amenable number.

721988128 is a deficient number, since it is larger than the sum of its proper divisors (699426062).

721988128 is a wasteful number, since it uses less digits than its factorization.

721988128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22562139 (or 22562131 counting only the distinct ones).

The product of its digits is 129024, while the sum is 46.

The square root of 721988128 is about 26869.8367691358. The cubic root of 721988128 is about 897.1051546955.

Subtracting 721988128 from its reverse (821889127), we obtain a palindrome (99900999).

The spelling of 721988128 in words is "seven hundred twenty-one million, nine hundred eighty-eight thousand, one hundred twenty-eight".