721689066 has 72 divisors (see below), whose sum is σ = 1898438880. Its totient is φ = 194057856.

The previous prime is 721689047. The next prime is 721689113. The reversal of 721689066 is 660986127.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 26505 + ... + 46323.

Almost surely, 2^721689066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721689066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (949219440).

721689066 is an abundant number, since it is smaller than the sum of its proper divisors (1176749814).

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

721689066 is a wasteful number, since it uses less digits than its factorization.

721689066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19868 (or 19848 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 721689066 is about 26864.2711793936. The cubic root of 721689066 is about 896.9812712577.

The spelling of 721689066 in words is "seven hundred twenty-one million, six hundred eighty-nine thousand, sixty-six".