21440481 has 4 divisors (see below), whose sum is σ = 28587312. Its totient is φ = 14293652.

The previous prime is 21440473. The next prime is 21440491. The reversal of 21440481 is 18404412.

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 a cyclic number.

It is not a de Polignac number, because 21440481 - 2³ = 21440473 is a prime.

It is a super-2 number, since 2×21440481² = 919388451022722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21440411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3573411 + ... + 3573416.

It is an arithmetic number, because the mean of its divisors is an integer number (7146828).

Almost surely, 2^21440481 is an apocalyptic number.

It is an amenable number.

21440481 is a deficient number, since it is larger than the sum of its proper divisors (7146831).

21440481 is an equidigital number, since it uses as much as digits as its factorization.

21440481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7146830.

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 21440481 is about 4630.3867009139. The cubic root of 21440481 is about 277.8080598039.

Adding to 21440481 its reverse (18404412), we get a palindrome (39844893).

The spelling of 21440481 in words is "twenty-one million, four hundred forty thousand, four hundred eighty-one".