861091 has 16 divisors (see below), whose sum is σ = 1099008. Its totient is φ = 655200.

The previous prime is 861089. The next prime is 861109. The reversal of 861091 is 190168.

861091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 861091 - 2¹ = 861089 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861001) 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, 3976 + ... + 4186.

It is an arithmetic number, because the mean of its divisors is an integer number (68688).

2⁸⁶¹⁰⁹¹ is an apocalyptic number.

861091 is a deficient number, since it is larger than the sum of its proper divisors (237917).

861091 is a wasteful number, since it uses less digits than its factorization.

861091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 861091 is about 927.9498908885. The cubic root of 861091 is about 95.1370505747.

The spelling of 861091 in words is "eight hundred sixty-one thousand, ninety-one".