21688686855 has 48 divisors (see below), whose sum is σ = 42794459136. Its totient is φ = 10058516160.

The previous prime is 21688686847. The next prime is 21688686863. The reversal of 21688686855 is 55868688612.

It is an interprime number because it is at equal distance from previous prime (21688686847) and next prime (21688686863).

It is not a de Polignac number, because 21688686855 - 2³ = 21688686847 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21688686792 and 21688686801.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 941127 + ... + 963896.

It is an arithmetic number, because the mean of its divisors is an integer number (891551232).

Almost surely, 2^21688686855 is an apocalyptic number.

21688686855 is a deficient number, since it is larger than the sum of its proper divisors (21105772281).

21688686855 is a wasteful number, since it uses less digits than its factorization.

21688686855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1905068 (or 1905065 counting only the distinct ones).

The product of its digits is 44236800, while the sum is 63.

The spelling of 21688686855 in words is "twenty-one billion, six hundred eighty-eight million, six hundred eighty-six thousand, eight hundred fifty-five".