21103000561 has 4 divisors (see below), whose sum is σ = 21103292992. Its totient is φ = 21102708132.

The previous prime is 21103000547. The next prime is 21103000573. The reversal of 21103000561 is 16500030112.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21103000561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103000511) 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, 48196 + ... + 211018.

It is an arithmetic number, because the mean of its divisors is an integer number (5275823248).

Almost surely, 2^21103000561 is an apocalyptic number.

It is an amenable number.

21103000561 is a deficient number, since it is larger than the sum of its proper divisors (292431).

21103000561 is a wasteful number, since it uses less digits than its factorization.

21103000561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292430.

The product of its (nonzero) digits is 180, while the sum is 19.

Adding to 21103000561 its reverse (16500030112), we get a palindrome (37603030673).

The spelling of 21103000561 in words is "twenty-one billion, one hundred three million, five hundred sixty-one", and thus it is an aban number.