21515127171 has 8 divisors (see below), whose sum is σ = 28696648704. Its totient is φ = 14338511880.

The previous prime is 21515127163. The next prime is 21515127197. The reversal of 21515127171 is 17172151512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21515127171 - 2³ = 21515127163 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21515127131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1216315 + ... + 1233876.

It is an arithmetic number, because the mean of its divisors is an integer number (3587081088).

Almost surely, 2^21515127171 is an apocalyptic number.

21515127171 is a deficient number, since it is larger than the sum of its proper divisors (7181521533).

21515127171 is a wasteful number, since it uses less digits than its factorization.

21515127171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2453121.

The product of its digits is 4900, while the sum is 33.

Adding to 21515127171 its reverse (17172151512), we get a palindrome (38687278683).

The spelling of 21515127171 in words is "twenty-one billion, five hundred fifteen million, one hundred twenty-seven thousand, one hundred seventy-one".