216509580 has 288 divisors, whose sum is σ = 811819008. Its totient is φ = 45619200.

The previous prime is 216509543. The next prime is 216509581. The reversal of 216509580 is 85905612.

It is a happy number.

216509580 is a `hidden beast` number, since 21 + 6 + 50 + 9 + 580 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (216509581) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 898260 + ... + 898500.

It is an arithmetic number, because the mean of its divisors is an integer number (2818816).

Almost surely, 2^216509580 is an apocalyptic number.

216509580 is a gapful number since it is divisible by the number (20) 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 216509580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (405909504).

216509580 is an abundant number, since it is smaller than the sum of its proper divisors (595309428).

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

216509580 is a wasteful number, since it uses less digits than its factorization.

216509580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 312 counting only the distinct ones).

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

The square root of 216509580 is about 14714.2645076130. The cubic root of 216509580 is about 600.4714627744.

It can be divided in two parts, 216 and 509580, that added together give a square (509796 = 714²).

The spelling of 216509580 in words is "two hundred sixteen million, five hundred nine thousand, five hundred eighty".