21941 has 4 divisors (see below), whose sum is σ = 22572. Its totient is φ = 21312.

The previous prime is 21937. The next prime is 21943. The reversal of 21941 is 14912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16900 + 5041 = 130^2 + 71^2 .

It is not a de Polignac number, because 21941 - 2² = 21937 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260 + ... + 333.

It is an arithmetic number, because the mean of its divisors is an integer number (5643).

2²¹⁹⁴¹ is an apocalyptic number.

It is an amenable number.

21941 is a deficient number, since it is larger than the sum of its proper divisors (631).

21941 is an equidigital number, since it uses as much as digits as its factorization.

21941 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630.

The product of its digits is 72, while the sum is 17.

The square root of 21941 is about 148.1249472574. The cubic root of 21941 is about 27.9953223479.

The spelling of 21941 in words is "twenty-one thousand, nine hundred forty-one".