217921320 has 256 divisors, whose sum is σ = 785203200. Its totient is φ = 53602560.

The previous prime is 217921313. The next prime is 217921321. The reversal of 217921320 is 23129712.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (217921321) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 769899 + ... + 770181.

It is an arithmetic number, because the mean of its divisors is an integer number (3067200).

Almost surely, 2^217921320 is an apocalyptic number.

217921320 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 217921320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392601600).

217921320 is an abundant number, since it is smaller than the sum of its proper divisors (567281880).

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

217921320 is a wasteful number, since it uses less digits than its factorization.

217921320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357 (or 347 counting only the distinct ones).

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

The square root of 217921320 is about 14762.1583787737. The cubic root of 217921320 is about 601.7737511774.

The spelling of 217921320 in words is "two hundred seventeen million, nine hundred twenty-one thousand, three hundred twenty".