171221687 has 16 divisors (see below), whose sum is σ = 211848000. Its totient is φ = 134756352.

The previous prime is 171221651. The next prime is 171221731. The reversal of 171221687 is 786122171.

171221687 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 171221687 - 2⁸ = 171221431 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171221627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12689 + ... + 22437.

It is an arithmetic number, because the mean of its divisors is an integer number (13240500).

Almost surely, 2^171221687 is an apocalyptic number.

171221687 is a deficient number, since it is larger than the sum of its proper divisors (40626313).

171221687 is a wasteful number, since it uses less digits than its factorization.

171221687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9962.

The product of its digits is 9408, while the sum is 35.

The square root of 171221687 is about 13085.1704994624. The cubic root of 171221687 is about 555.2896650947.

The spelling of 171221687 in words is "one hundred seventy-one million, two hundred twenty-one thousand, six hundred eighty-seven".