721668606 has 16 divisors (see below), whose sum is σ = 1443696384. Its totient is φ = 240496344.

The previous prime is 721668557. The next prime is 721668641. The reversal of 721668606 is 606866127.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16125 + ... + 41271.

It is an arithmetic number, because the mean of its divisors is an integer number (90231024).

Almost surely, 2^721668606 is an apocalyptic number.

721668606 is an abundant number, since it is smaller than the sum of its proper divisors (722027778).

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

721668606 is a wasteful number, since it uses less digits than its factorization.

721668606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29935.

The product of its (nonzero) digits is 145152, while the sum is 42.

The square root of 721668606 is about 26863.8903735107. The cubic root of 721668606 is about 896.9727946569.

The spelling of 721668606 in words is "seven hundred twenty-one million, six hundred sixty-eight thousand, six hundred six".