21022481 has 4 divisors (see below), whose sum is σ = 21033012. Its totient is φ = 21011952.

The previous prime is 21022471. The next prime is 21022517. The reversal of 21022481 is 18422012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 410881 + 20611600 = 641^2 + 4540^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022481 - 2¹⁰ = 21021457 is a prime.

It is a super-2 number, since 2×21022481² = 883889414790722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21022411) 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, 1250 + ... + 6603.

It is an arithmetic number, because the mean of its divisors is an integer number (5258253).

Almost surely, 2^21022481 is an apocalyptic number.

It is an amenable number.

21022481 is a deficient number, since it is larger than the sum of its proper divisors (10531).

21022481 is an equidigital number, since it uses as much as digits as its factorization.

21022481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10530.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21022481 is about 4585.0279170361. The cubic root of 21022481 is about 275.9908323287.

Subtracting from 21022481 its product of nonzero digits (256), we obtain a square (21022225 = 4585²).

Adding to 21022481 its reverse (18422012), we get a palindrome (39444493).

The spelling of 21022481 in words is "twenty-one million, twenty-two thousand, four hundred eighty-one".