21511244553 has 16 divisors (see below), whose sum is σ = 29010389760. Its totient is φ = 14176536704.

The previous prime is 21511244509. The next prime is 21511244563. The reversal of 21511244553 is 35544211512.

It is a cyclic number.

It is not a de Polignac number, because 21511244553 - 2¹⁰ = 21511243529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21511244563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2340475 + ... + 2349647.

It is an arithmetic number, because the mean of its divisors is an integer number (1813149360).

Almost surely, 2^21511244553 is an apocalyptic number.

It is an amenable number.

21511244553 is a deficient number, since it is larger than the sum of its proper divisors (7499145207).

21511244553 is an equidigital number, since it uses as much as digits as its factorization.

21511244553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18048.

The product of its digits is 24000, while the sum is 33.

The spelling of 21511244553 in words is "twenty-one billion, five hundred eleven million, two hundred forty-four thousand, five hundred fifty-three".