221940 has 60 divisors (see below), whose sum is σ = 701316. Its totient is φ = 58752.

The previous prime is 221909. The next prime is 221941. The reversal of 221940 is 49122.

It can be written as a sum of positive squares in 2 ways, for example, as 104976 + 116964 = 324^2 + 342^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 12.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221940.

It is not an unprimeable number, because it can be changed into a prime (221941) by changing a digit.

221940 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1552 + ... + 1688.

2²²¹⁹⁴⁰ is an apocalyptic number.

221940 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 221940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (350658).

221940 is an abundant number, since it is smaller than the sum of its proper divisors (479376).

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

221940 is a wasteful number, since it uses less digits than its factorization.

221940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 221940 is about 471.1050838189. The cubic root of 221940 is about 60.5450339745.

The spelling of 221940 in words is "two hundred twenty-one thousand, nine hundred forty".