16721557056 has 224 divisors, whose sum is σ = 50103836800. Its totient is φ = 5536014336.

The previous prime is 16721557049. The next prime is 16721557063. The reversal of 16721557056 is 65075512761.

16721557056 is a `hidden beast` number, since 1 + 6 + 7 + 21 + 5 + 570 + 56 = 666.

16721557056 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (16721557049) and next prime (16721557063).

It is a super-2 number, since 2×16721557056² (a number of 21 digits) contains 22 as substring.

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 31 ways as a sum of consecutive naturals, for example, 27013515 + ... + 27014133.

Almost surely, 2^16721557056 is an apocalyptic number.

16721557056 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16721557056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25051918400).

16721557056 is an abundant number, since it is smaller than the sum of its proper divisors (33382279744).

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

16721557056 is an frugal number, since it uses more digits than its factorization.

16721557056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845 (or 817 counting only the distinct ones).

The product of its (nonzero) digits is 441000, while the sum is 45.

The spelling of 16721557056 in words is "sixteen billion, seven hundred twenty-one million, five hundred fifty-seven thousand, fifty-six".