21563349 has 4 divisors (see below), whose sum is σ = 28751136. Its totient is φ = 14375564.

The previous prime is 21563329. The next prime is 21563363. The reversal of 21563349 is 94336512.

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 21563349 - 2⁸ = 21563093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563329) 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, 3593889 + ... + 3593894.

It is an arithmetic number, because the mean of its divisors is an integer number (7187784).

Almost surely, 2^21563349 is an apocalyptic number.

It is an amenable number.

21563349 is a deficient number, since it is larger than the sum of its proper divisors (7187787).

21563349 is an equidigital number, since it uses as much as digits as its factorization.

21563349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7187786.

The product of its digits is 19440, while the sum is 33.

The square root of 21563349 is about 4643.6353215988. The cubic root of 21563349 is about 278.3377233661.

It can be divided in two parts, 21563 and 349, that added together give a palindrome (21912).

The spelling of 21563349 in words is "twenty-one million, five hundred sixty-three thousand, three hundred forty-nine".