21111065553 has 16 divisors (see below), whose sum is σ = 28365120576. Its totient is φ = 13965611520.

The previous prime is 21111065539. The next prime is 21111065669. The reversal of 21111065553 is 35556011112.

It is not a de Polignac number, because 21111065553 - 2⁶ = 21111065489 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21111065553.

It is not an unprimeable number, because it can be changed into a prime (21111065513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1155298 + ... + 1173428.

It is an arithmetic number, because the mean of its divisors is an integer number (1772820036).

Almost surely, 2^21111065553 is an apocalyptic number.

It is an amenable number.

21111065553 is a deficient number, since it is larger than the sum of its proper divisors (7254055023).

21111065553 is a wasteful number, since it uses less digits than its factorization.

21111065553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21104.

The product of its (nonzero) digits is 4500, while the sum is 30.

Adding to 21111065553 its reverse (35556011112), we get a palindrome (56667076665).

The spelling of 21111065553 in words is "twenty-one billion, one hundred eleven million, sixty-five thousand, five hundred fifty-three".