16621720556 has 48 divisors (see below), whose sum is σ = 35321025600. Its totient is φ = 6704504064.

The previous prime is 16621720547. The next prime is 16621720561. The reversal of 16621720556 is 65502712661.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77150 + ... + 197978.

It is an arithmetic number, because the mean of its divisors is an integer number (735854700).

Almost surely, 2^16621720556 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 16621720556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17660512800).

16621720556 is an abundant number, since it is smaller than the sum of its proper divisors (18699305044).

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

16621720556 is a wasteful number, since it uses less digits than its factorization.

16621720556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120891 (or 120855 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 41.

The spelling of 16621720556 in words is "sixteen billion, six hundred twenty-one million, seven hundred twenty thousand, five hundred fifty-six".