721668006106 has 8 divisors (see below), whose sum is σ = 1083440869524. Its totient is φ = 360521049600.

The previous prime is 721668006079. The next prime is 721668006107. The reversal of 721668006106 is 601600866127.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 705574800225 + 16093205881 = 839985^2 + 126859^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×721668006106² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (721668006107) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 156473845 + ... + 156478456.

Almost surely, 2^721668006106 is an apocalyptic number.

721668006106 is a deficient number, since it is larger than the sum of its proper divisors (361772863418).

721668006106 is a wasteful number, since it uses less digits than its factorization.

721668006106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312953456.

The product of its (nonzero) digits is 145152, while the sum is 43.

The spelling of 721668006106 in words is "seven hundred twenty-one billion, six hundred sixty-eight million, six thousand, one hundred six".