21005463 has 16 divisors (see below), whose sum is σ = 29352960. Its totient is φ = 13336224.

The previous prime is 21005441. The next prime is 21005473. The reversal of 21005463 is 36450012.

It is a happy number.

It is not a de Polignac number, because 21005463 - 2⁶ = 21005399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19698 + ... + 20736.

It is an arithmetic number, because the mean of its divisors is an integer number (1834560).

Almost surely, 2^21005463 is an apocalyptic number.

21005463 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21005463 is a deficient number, since it is larger than the sum of its proper divisors (8347497).

21005463 is a wasteful number, since it uses less digits than its factorization.

21005463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1358.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21005463 is about 4583.1717183627. The cubic root of 21005463 is about 275.9163393778.

Adding to 21005463 its reverse (36450012), we get a palindrome (57455475).

The spelling of 21005463 in words is "twenty-one million, five thousand, four hundred sixty-three".