8538171721 has 4 divisors (see below), whose sum is σ = 8987549200. Its totient is φ = 8088794244.

The previous prime is 8538171709. The next prime is 8538171727. The reversal of 8538171721 is 1271718358.

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.

It is a cyclic number.

It is not a de Polignac number, because 8538171721 - 2⁹ = 8538171209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8538171727) 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, 224688711 + ... + 224688748.

It is an arithmetic number, because the mean of its divisors is an integer number (2246887300).

Almost surely, 2^8538171721 is an apocalyptic number.

It is an amenable number.

8538171721 is a deficient number, since it is larger than the sum of its proper divisors (449377479).

8538171721 is a wasteful number, since it uses less digits than its factorization.

8538171721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449377478.

The product of its digits is 94080, while the sum is 43.

The square root of 8538171721 is about 92402.2279006302. The cubic root of 8538171721 is about 2043.8779657134.

The spelling of 8538171721 in words is "eight billion, five hundred thirty-eight million, one hundred seventy-one thousand, seven hundred twenty-one".