872170891 has 4 divisors (see below), whose sum is σ = 875274984. Its totient is φ = 869066800.

The previous prime is 872170843. The next prime is 872170903. The reversal of 872170891 is 198071278.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 198071278 = 2 ⋅99035639.

It is a cyclic number.

It is not a de Polignac number, because 872170891 - 2⁹ = 872170379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (872170801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1551625 + ... + 1552186.

It is an arithmetic number, because the mean of its divisors is an integer number (218818746).

Almost surely, 2^872170891 is an apocalyptic number.

872170891 is a deficient number, since it is larger than the sum of its proper divisors (3104093).

872170891 is a wasteful number, since it uses less digits than its factorization.

872170891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3104092.

The product of its (nonzero) digits is 56448, while the sum is 43.

The square root of 872170891 is about 29532.5395284591. The cubic root of 872170891 is about 955.4336420487.

The spelling of 872170891 in words is "eight hundred seventy-two million, one hundred seventy thousand, eight hundred ninety-one".