221705920 has 56 divisors (see below), whose sum is σ = 529218144. Its totient is φ = 88467456.

The previous prime is 221705863. The next prime is 221705923. The reversal of 221705920 is 29507122.

It is not an unprimeable number, because it can be changed into a prime (221705923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 232164 + ... + 233116.

It is an arithmetic number, because the mean of its divisors is an integer number (9450324).

Almost surely, 2^221705920 is an apocalyptic number.

221705920 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 221705920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (264609072).

221705920 is an abundant number, since it is smaller than the sum of its proper divisors (307512224).

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

221705920 is an equidigital number, since it uses as much as digits as its factorization.

221705920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1697 (or 1687 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 221705920 is about 14889.7924767271. The cubic root of 221705920 is about 605.2374088180.

The spelling of 221705920 in words is "two hundred twenty-one million, seven hundred five thousand, nine hundred twenty".