21422281 has 4 divisors (see below), whose sum is σ = 21460500. Its totient is φ = 21384064.

The previous prime is 21422273. The next prime is 21422321. The reversal of 21422281 is 18222412.

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 12960000 + 8462281 = 3600^2 + 2909^2 .

It is a cyclic number.

It is not a de Polignac number, because 21422281 - 2³ = 21422273 is a prime.

It is a super-2 number, since 2×21422281² = 917828246485922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21422221) 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, 18256 + ... + 19393.

It is an arithmetic number, because the mean of its divisors is an integer number (5365125).

Almost surely, 2^21422281 is an apocalyptic number.

It is an amenable number.

21422281 is a deficient number, since it is larger than the sum of its proper divisors (38219).

21422281 is an equidigital number, since it uses as much as digits as its factorization.

21422281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38218.

The product of its digits is 512, while the sum is 22.

The square root of 21422281 is about 4628.4210050513. The cubic root of 21422281 is about 277.7294306909.

Adding to 21422281 its reverse (18222412), we get a palindrome (39644693).

The spelling of 21422281 in words is "twenty-one million, four hundred twenty-two thousand, two hundred eighty-one".