217323820 has 72 divisors (see below), whose sum is σ = 536294304. Its totient is φ = 73753344.

The previous prime is 217323809. The next prime is 217323823. The reversal of 217323820 is 28323712.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a zygodrome in base 6.

It is not an unprimeable number, because it can be changed into a prime (217323823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 99864 + ... + 102016.

It is an arithmetic number, because the mean of its divisors is an integer number (7448532).

Almost surely, 2^217323820 is an apocalyptic number.

217323820 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 217323820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (268147152).

217323820 is an abundant number, since it is smaller than the sum of its proper divisors (318970484).

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

217323820 is a wasteful number, since it uses less digits than its factorization.

217323820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2279 (or 2270 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 217323820 is about 14741.9069322798. The cubic root of 217323820 is about 601.2232636080.

It can be divided in two parts, 21732 and 3820, that added together give a palindrome (25552).

The spelling of 217323820 in words is "two hundred seventeen million, three hundred twenty-three thousand, eight hundred twenty".