16556221800 has 576 divisors, whose sum is σ = 63249076800. Its totient is φ = 4006195200.

The previous prime is 16556221757. The next prime is 16556221831. The reversal of 16556221800 is 812265561.

16556221800 is a `hidden beast` number, since 1 + 6 + 556 + 2 + 21 + 80 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 23959455 + ... + 23960145.

It is an arithmetic number, because the mean of its divisors is an integer number (109807425).

Almost surely, 2^16556221800 is an apocalyptic number.

16556221800 is a gapful number since it is divisible by the number (10) 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 16556221800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31624538400).

16556221800 is an abundant number, since it is smaller than the sum of its proper divisors (46692855000).

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

16556221800 is a wasteful number, since it uses less digits than its factorization.

16556221800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 747 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The spelling of 16556221800 in words is "sixteen billion, five hundred fifty-six million, two hundred twenty-one thousand, eight hundred".