221000 has 64 divisors (see below), whose sum is σ = 589680. Its totient is φ = 76800.

The previous prime is 220973. The next prime is 221021. The reversal of 221000 is 122.

It can be written as a sum of positive squares in 8 ways, for example, as 3844 + 217156 = 62^2 + 466^2 .

It is a Harshad number since it is a multiple of its sum of digits (5).

It is a nialpdrome in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12992 + ... + 13008.

2²²¹⁰⁰⁰ is an apocalyptic number.

221000 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 221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (294840).

221000 is an abundant number, since it is smaller than the sum of its proper divisors (368680).

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

221000 is a wasteful number, since it uses less digits than its factorization.

221000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51 (or 37 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 5.

The square root of 221000 is about 470.1063709417. The cubic root of 221000 is about 60.4594359601.

Adding to 221000 its reverse (122), we get a palindrome (221122).

The spelling of 221000 in words is "two hundred twenty-one thousand", and thus it is an iban number.