21055100563 has 16 divisors (see below), whose sum is σ = 24485583616. Its totient is φ = 17730951840.

The previous prime is 21055100557. The next prime is 21055100567. The reversal of 21055100563 is 36500155012.

It is a de Polignac number, because none of the positive numbers 2^k-21055100563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055100567) 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, 349120 + ... + 404962.

It is an arithmetic number, because the mean of its divisors is an integer number (1530348976).

Almost surely, 2^21055100563 is an apocalyptic number.

21055100563 is a deficient number, since it is larger than the sum of its proper divisors (3430483053).

21055100563 is an equidigital number, since it uses as much as digits as its factorization.

21055100563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56794.

The product of its (nonzero) digits is 4500, while the sum is 28.

Adding to 21055100563 its reverse (36500155012), we get a palindrome (57555255575).

The spelling of 21055100563 in words is "twenty-one billion, fifty-five million, one hundred thousand, five hundred sixty-three".