861989 has 4 divisors (see below), whose sum is σ = 885324. Its totient is φ = 838656.

The previous prime is 861979. The next prime is 861997. The reversal of 861989 is 989168.

861989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 429025 + 432964 = 655^2 + 658^2 .

It is a cyclic number.

It is not a de Polignac number, because 861989 - 2⁸ = 861733 is a prime.

It is a super-2 number, since 2×861989² = 1486050072242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861929) 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, 11612 + ... + 11685.

It is an arithmetic number, because the mean of its divisors is an integer number (221331).

2⁸⁶¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

861989 is a deficient number, since it is larger than the sum of its proper divisors (23335).

861989 is a wasteful number, since it uses less digits than its factorization.

861989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23334.

The product of its digits is 31104, while the sum is 41.

The square root of 861989 is about 928.4336271377. The cubic root of 861989 is about 95.1701107237.

The spelling of 861989 in words is "eight hundred sixty-one thousand, nine hundred eighty-nine".