21543653808 has 40 divisors (see below), whose sum is σ = 61838266800. Its totient is φ = 7181217792.

The previous prime is 21543653797. The next prime is 21543653837. The reversal of 21543653808 is 80835634512.

21543653808 is a `hidden beast` number, since 21 + 543 + 6 + 5 + 3 + 80 + 8 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24934353 + ... + 24935216.

It is an arithmetic number, because the mean of its divisors is an integer number (1545956670).

Almost surely, 2^21543653808 is an apocalyptic number.

It is an amenable number.

21543653808 is an abundant number, since it is smaller than the sum of its proper divisors (40294612992).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21543653808 is a wasteful number, since it uses less digits than its factorization.

21543653808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49869586 (or 49869574 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 45.

The spelling of 21543653808 in words is "twenty-one billion, five hundred forty-three million, six hundred fifty-three thousand, eight hundred eight".