870991 has 4 divisors (see below), whose sum is σ = 950184. Its totient is φ = 791800.

The previous prime is 870983. The next prime is 870997. The reversal of 870991 is 199078.

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 870991 - 2³ = 870983 is a prime.

It is a Duffinian number.

870991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (870997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39580 + ... + 39601.

It is an arithmetic number, because the mean of its divisors is an integer number (237546).

2⁸⁷⁰⁹⁹¹ is an apocalyptic number.

870991 is a deficient number, since it is larger than the sum of its proper divisors (79193).

870991 is a wasteful number, since it uses less digits than its factorization.

870991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79192.

The product of its (nonzero) digits is 4536, while the sum is 34.

The square root of 870991 is about 933.2689858771. The cubic root of 870991 is about 95.5002604088.

The spelling of 870991 in words is "eight hundred seventy thousand, nine hundred ninety-one".