216685217725021 has 12 divisors (see below), whose sum is σ = 226521481340700. Its totient is φ = 207259039064000.

The previous prime is 216685217725019. The next prime is 216685217725027. The reversal of 216685217725021 is 120527712586612.

It can be written as a sum of positive squares in 2 ways, for example, as 56251050004900 + 160434167720121 = 7500070^2 + 12666261^2 .

It is not a de Polignac number, because 216685217725021 - 2¹ = 216685217725019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216685217725027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16660521 + ... + 26663521.

It is an arithmetic number, because the mean of its divisors is an integer number (18876790111725).

Almost surely, 2^{216685217725021} is an apocalyptic number.

It is an amenable number.

216685217725021 is a deficient number, since it is larger than the sum of its proper divisors (9836263615679).

216685217725021 is a wasteful number, since it uses less digits than its factorization.

216685217725021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10043996 (or 10043973 counting only the distinct ones).

The product of its (nonzero) digits is 5644800, while the sum is 55.

The spelling of 216685217725021 in words is "two hundred sixteen trillion, six hundred eighty-five billion, two hundred seventeen million, seven hundred twenty-five thousand, twenty-one".