217921140 has 72 divisors (see below), whose sum is σ = 675118080. Its totient is φ = 56873664.

The previous prime is 217921091. The next prime is 217921141. The reversal of 217921140 is 41129712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217921141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4420 + ... + 21339.

It is an arithmetic number, because the mean of its divisors is an integer number (9376640).

Almost surely, 2^217921140 is an apocalyptic number.

217921140 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 217921140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (337559040).

217921140 is an abundant number, since it is smaller than the sum of its proper divisors (457196940).

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

217921140 is a wasteful number, since it uses less digits than its factorization.

217921140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25821 (or 25816 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 217921140 is about 14762.1522821030. The cubic root of 217921140 is about 601.7735854918.

The spelling of 217921140 in words is "two hundred seventeen million, nine hundred twenty-one thousand, one hundred forty".