221730 has 32 divisors (see below), whose sum is σ = 561600. Its totient is φ = 55872.

The previous prime is 221729. The next prime is 221737. The reversal of 221730 is 37122.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 376 + ... + 764.

It is an arithmetic number, because the mean of its divisors is an integer number (17550).

2²²¹⁷³⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (280800).

221730 is an abundant number, since it is smaller than the sum of its proper divisors (339870).

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

221730 is a wasteful number, since it uses less digits than its factorization.

221730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418.

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 221730 is about 470.8821508616. The cubic root of 221730 is about 60.5259320110.

Adding to 221730 its reverse (37122), we get a palindrome (258852).

The spelling of 221730 in words is "two hundred twenty-one thousand, seven hundred thirty".