21941281 has 4 divisors (see below), whose sum is σ = 22004500. Its totient is φ = 21878064.

The previous prime is 21941279. The next prime is 21941291. The reversal of 21941281 is 18214912.

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 9579025 + 12362256 = 3095^2 + 3516^2 .

It is a cyclic number.

It is not a de Polignac number, because 21941281 - 2¹ = 21941279 is a prime.

It is a super-2 number, since 2×21941281² = 962839623841922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21941261) 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, 31086 + ... + 31783.

It is an arithmetic number, because the mean of its divisors is an integer number (5501125).

Almost surely, 2^21941281 is an apocalyptic number.

It is an amenable number.

21941281 is a deficient number, since it is larger than the sum of its proper divisors (63219).

21941281 is an equidigital number, since it uses as much as digits as its factorization.

21941281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63218.

The product of its digits is 1152, while the sum is 28.

The square root of 21941281 is about 4684.1521111083. The cubic root of 21941281 is about 279.9544186006.

It can be divided in two parts, 21941 and 281, that added together give a palindrome (22222).

The spelling of 21941281 in words is "twenty-one million, nine hundred forty-one thousand, two hundred eighty-one".