171887021687 has 4 divisors (see below), whose sum is σ = 179360370480. Its totient is φ = 164413672896.

The previous prime is 171887021681. The next prime is 171887021699. The reversal of 171887021687 is 786120788171.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 171887021687 - 2¹² = 171887017591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171887021681) 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, 3736674362 + ... + 3736674407.

It is an arithmetic number, because the mean of its divisors is an integer number (44840092620).

Almost surely, 2^171887021687 is an apocalyptic number.

171887021687 is a deficient number, since it is larger than the sum of its proper divisors (7473348793).

171887021687 is an equidigital number, since it uses as much as digits as its factorization.

171887021687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7473348792.

The product of its (nonzero) digits is 2107392, while the sum is 56.

The spelling of 171887021687 in words is "one hundred seventy-one billion, eight hundred eighty-seven million, twenty-one thousand, six hundred eighty-seven".