21440505 has 8 divisors (see below), whose sum is σ = 34304832. Its totient is φ = 11434928.

The previous prime is 21440491. The next prime is 21440527. The reversal of 21440505 is 50504412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21440505 - 2⁵ = 21440473 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 714669 + ... + 714698.

It is an arithmetic number, because the mean of its divisors is an integer number (4288104).

Almost surely, 2^21440505 is an apocalyptic number.

It is an amenable number.

21440505 is a deficient number, since it is larger than the sum of its proper divisors (12864327).

21440505 is a wasteful number, since it uses less digits than its factorization.

21440505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429375.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21440505 is about 4630.3892924893. The cubic root of 21440505 is about 277.8081634612.

Adding to 21440505 its reverse (50504412), we get a palindrome (71944917).

It can be divided in two parts, 21440 and 505, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21440505 in words is "twenty-one million, four hundred forty thousand, five hundred five".