21485617756855 has 16 divisors (see below), whose sum is σ = 29653671539520. Its totient is φ = 14639154296832.

The previous prime is 21485617756849. The next prime is 21485617756861. The reversal of 21485617756855 is 55865771658412.

It is an interprime number because it is at equal distance from previous prime (21485617756849) and next prime (21485617756861).

It is a cyclic number.

It is not a de Polignac number, because 21485617756855 - 2¹¹ = 21485617754807 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1955009770 + ... + 1955020759.

It is an arithmetic number, because the mean of its divisors is an integer number (1853354471220).

Almost surely, 2^{21485617756855} is an apocalyptic number.

21485617756855 is a deficient number, since it is larger than the sum of its proper divisors (8168053782665).

21485617756855 is a wasteful number, since it uses less digits than its factorization.

21485617756855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3910030698.

The product of its digits is 564480000, while the sum is 70.

The spelling of 21485617756855 in words is "twenty-one trillion, four hundred eighty-five billion, six hundred seventeen million, seven hundred fifty-six thousand, eight hundred fifty-five".