21563463 has 16 divisors (see below), whose sum is σ = 30537216. Its totient is φ = 13488000.

The previous prime is 21563453. The next prime is 21563467. The reversal of 21563463 is 36436512.

It is not a de Polignac number, because 21563463 - 2¹⁰ = 21562439 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21563463.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563467) 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, 28338 + ... + 29088.

It is an arithmetic number, because the mean of its divisors is an integer number (1908576).

Almost surely, 2^21563463 is an apocalyptic number.

21563463 is a deficient number, since it is larger than the sum of its proper divisors (8973753).

21563463 is a wasteful number, since it uses less digits than its factorization.

21563463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1334.

The product of its digits is 12960, while the sum is 30.

The square root of 21563463 is about 4643.6475964483. The cubic root of 21563463 is about 278.3382138658.

Adding to 21563463 its reverse (36436512), we get a palindrome (57999975).

The spelling of 21563463 in words is "twenty-one million, five hundred sixty-three thousand, four hundred sixty-three".