16561215216 has 180 divisors, whose sum is σ = 58063153512. Its totient is φ = 4367768832.

The previous prime is 16561215199. The next prime is 16561215247. The reversal of 16561215216 is 61251216561.

16561215216 is a `hidden beast` number, since 1 + 6 + 5 + 6 + 121 + 521 + 6 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1455 + ... + 182001.

Almost surely, 2^16561215216 is an apocalyptic number.

16561215216 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 16561215216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29031576756).

16561215216 is an abundant number, since it is smaller than the sum of its proper divisors (41501938296).

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

16561215216 is a wasteful number, since it uses less digits than its factorization.

16561215216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180588 (or 180572 counting only the distinct ones).

The product of its digits is 21600, while the sum is 36.

The spelling of 16561215216 in words is "sixteen billion, five hundred sixty-one million, two hundred fifteen thousand, two hundred sixteen".