21561505133 has 32 divisors (see below), whose sum is σ = 26090400000. Its totient is φ = 17790010560.

The previous prime is 21561505123. The next prime is 21561505139. The reversal of 21561505133 is 33150516512.

It is not a de Polignac number, because 21561505133 - 2¹² = 21561501037 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21561505133.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21561505139) 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 31 ways as a sum of consecutive naturals, for example, 3468398 + ... + 3474608.

It is an arithmetic number, because the mean of its divisors is an integer number (815325000).

Almost surely, 2^21561505133 is an apocalyptic number.

It is an amenable number.

21561505133 is a deficient number, since it is larger than the sum of its proper divisors (4528894867).

21561505133 is an equidigital number, since it uses as much as digits as its factorization.

21561505133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6610 (or 6596 counting only the distinct ones).

The product of its (nonzero) digits is 13500, while the sum is 32.

The spelling of 21561505133 in words is "twenty-one billion, five hundred sixty-one million, five hundred five thousand, one hundred thirty-three".