215665560 has 144 divisors (see below), whose sum is σ = 770580720. Its totient is φ = 52272000.

The previous prime is 215665531. The next prime is 215665573. The reversal of 215665560 is 65566512.

It is a happy number.

It is a super-2 number, since 2×215665560² = 93023267540227200, which contains 22 as substring.

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, 41085 + ... + 46035.

It is an arithmetic number, because the mean of its divisors is an integer number (5351255).

Almost surely, 2^215665560 is an apocalyptic number.

215665560 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 215665560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (385290360).

215665560 is an abundant number, since it is smaller than the sum of its proper divisors (554915160).

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

215665560 is a wasteful number, since it uses less digits than its factorization.

215665560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4990 (or 4972 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 215665560 is about 14685.5561692433. The cubic root of 215665560 is about 599.6901733733.

It can be divided in two parts, 215665 and 560, that added together give a square (216225 = 465²).

The spelling of 215665560 in words is "two hundred fifteen million, six hundred sixty-five thousand, five hundred sixty".