219981 has 4 divisors (see below), whose sum is σ = 293312. Its totient is φ = 146652.

The previous prime is 219979. The next prime is 219983. The reversal of 219981 is 189912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (219979) and next prime (219983).

It is not a de Polignac number, because 219981 - 2¹ = 219979 is a prime.

It is a super-2 number, since 2×219981² = 96783280722, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

219981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (219983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36661 + ... + 36666.

It is an arithmetic number, because the mean of its divisors is an integer number (73328).

2²¹⁹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

219981 is a deficient number, since it is larger than the sum of its proper divisors (73331).

219981 is an equidigital number, since it uses as much as digits as its factorization.

219981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73330.

The product of its digits is 1296, while the sum is 30.

The square root of 219981 is about 469.0213214770. The cubic root of 219981 is about 60.3663694482.

The spelling of 219981 in words is "two hundred nineteen thousand, nine hundred eighty-one".