21845563 has 2 divisors, whose sum is σ = 21845564. Its totient is φ = 21845562.

The previous prime is 21845557. The next prime is 21845597. The reversal of 21845563 is 36554812.

It is an a-pointer prime, because the next prime (21845597) can be obtained adding 21845563 to its sum of digits (34).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21845563 - 2⁵ = 21845531 is a prime.

It is not a weakly prime, because it can be changed into another prime (21845513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922781 + 10922782.

It is an arithmetic number, because the mean of its divisors is an integer number (10922782).

Almost surely, 2^21845563 is an apocalyptic number.

21845563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845563 is an equidigital number, since it uses as much as digits as its factorization.

21845563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28800, while the sum is 34.

The square root of 21845563 is about 4673.9237263781. The cubic root of 21845563 is about 279.5467283622.

The spelling of 21845563 in words is "twenty-one million, eight hundred forty-five thousand, five hundred sixty-three".