171221661665615 has 16 divisors (see below), whose sum is σ = 224145214488576. Its totient is φ = 124524570535200.

The previous prime is 171221661665609. The next prime is 171221661665627. The reversal of 171221661665615 is 516566166122171.

It is not a de Polignac number, because 171221661665615 - 2¹⁴ = 171221661649231 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23698994 + ... + 30068016.

It is an arithmetic number, because the mean of its divisors is an integer number (14009075905536).

Almost surely, 2^{171221661665615} is an apocalyptic number.

171221661665615 is a deficient number, since it is larger than the sum of its proper divisors (52923552822961).

171221661665615 is a wasteful number, since it uses less digits than its factorization.

171221661665615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6857830.

The product of its digits is 5443200, while the sum is 56.

The spelling of 171221661665615 in words is "one hundred seventy-one trillion, two hundred twenty-one billion, six hundred sixty-one million, six hundred sixty-five thousand, six hundred fifteen".