72171170221 has 4 divisors (see below), whose sum is σ = 72192736512. Its totient is φ = 72149603932.

The previous prime is 72171170213. The next prime is 72171170263. The reversal of 72171170221 is 12207117127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12207117127 = 56629 ⋅215563.

It is a cyclic number.

It is not a de Polignac number, because 72171170221 - 2³ = 72171170213 is a prime.

It is a super-2 number, since 2×72171170221² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72171174221) 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, 10778125 + ... + 10784818.

It is an arithmetic number, because the mean of its divisors is an integer number (18048184128).

Almost surely, 2^72171170221 is an apocalyptic number.

It is an amenable number.

72171170221 is a deficient number, since it is larger than the sum of its proper divisors (21566291).

72171170221 is a wasteful number, since it uses less digits than its factorization.

72171170221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21566290.

The product of its (nonzero) digits is 2744, while the sum is 31.

Adding to 72171170221 its reverse (12207117127), we get a palindrome (84378287348).

The spelling of 72171170221 in words is "seventy-two billion, one hundred seventy-one million, one hundred seventy thousand, two hundred twenty-one".