21505008573 has 20 divisors (see below), whose sum is σ = 32436669408. Its totient is φ = 14197475880.

The previous prime is 21505008571. The next prime is 21505008593. The reversal of 21505008573 is 37580050512.

21505008573 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 500 + 85 + 73 = 666.

It is not a de Polignac number, because 21505008573 - 2¹ = 21505008571 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505008571) 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 19 ways as a sum of consecutive naturals, for example, 1280463 + ... + 1297148.

Almost surely, 2^21505008573 is an apocalyptic number.

It is an amenable number.

21505008573 is a deficient number, since it is larger than the sum of its proper divisors (10931660835).

21505008573 is a wasteful number, since it uses less digits than its factorization.

21505008573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2577726 (or 2577717 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 36.

The spelling of 21505008573 in words is "twenty-one billion, five hundred five million, eight thousand, five hundred seventy-three".