217912320 has 132 divisors (see below), whose sum is σ = 755220180. Its totient is φ = 58097664.

The previous prime is 217912297. The next prime is 217912333. The reversal of 217912320 is 23219712.

It can be written as a sum of positive squares in 2 ways, for example, as 32080896 + 185831424 = 5664^2 + 13632^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43716 + ... + 48444.

It is an arithmetic number, because the mean of its divisors is an integer number (5721365).

Almost surely, 2^217912320 is an apocalyptic number.

217912320 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 217912320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (377610090).

217912320 is an abundant number, since it is smaller than the sum of its proper divisors (537307860).

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

217912320 is a wasteful number, since it uses less digits than its factorization.

217912320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4760 (or 4739 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 217912320 is about 14761.8535421538. The cubic root of 217912320 is about 601.7654667833.

The spelling of 217912320 in words is "two hundred seventeen million, nine hundred twelve thousand, three hundred twenty".