216601721171 has 4 divisors (see below), whose sum is σ = 236292786744. Its totient is φ = 196910655600.

The previous prime is 216601721159. The next prime is 216601721179. The reversal of 216601721171 is 171127106612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216601721171 - 2¹⁰ = 216601720147 is a prime.

It is a super-2 number, since 2×216601721171² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216601721179) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9845532770 + ... + 9845532791.

It is an arithmetic number, because the mean of its divisors is an integer number (59073196686).

Almost surely, 2^216601721171 is an apocalyptic number.

216601721171 is a deficient number, since it is larger than the sum of its proper divisors (19691065573).

216601721171 is a wasteful number, since it uses less digits than its factorization.

216601721171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19691065572.

The product of its (nonzero) digits is 7056, while the sum is 35.

Adding to 216601721171 its reverse (171127106612), we get a palindrome (387728827783).

The spelling of 216601721171 in words is "two hundred sixteen billion, six hundred one million, seven hundred twenty-one thousand, one hundred seventy-one".