21685193945855 has 32 divisors (see below), whose sum is σ = 29679003583488. Its totient is φ = 15056397241600.

The previous prime is 21685193945839. The next prime is 21685193945861. The reversal of 21685193945855 is 55854939158612.

It is not a de Polignac number, because 21685193945855 - 2⁴ = 21685193945839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15792419 + ... + 17110548.

It is an arithmetic number, because the mean of its divisors is an integer number (927468861984).

Almost surely, 2^{21685193945855} is an apocalyptic number.

21685193945855 is a deficient number, since it is larger than the sum of its proper divisors (7993809637633).

21685193945855 is a wasteful number, since it uses less digits than its factorization.

21685193945855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32903527.

The product of its digits is 466560000, while the sum is 71.

The spelling of 21685193945855 in words is "twenty-one trillion, six hundred eighty-five billion, one hundred ninety-three million, nine hundred forty-five thousand, eight hundred fifty-five".