861881 has 2 divisors, whose sum is σ = 861882. Its totient is φ = 861880.

The previous prime is 861877. The next prime is 861899. The reversal of 861881 is 188168.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 477481 + 384400 = 691^2 + 620^2 .

It is a cyclic number.

It is not a de Polignac number, because 861881 - 2² = 861877 is a prime.

It is a super-2 number, since 2×861881² = 1485677716322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (861871) 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 as a sum of consecutive naturals, namely, 430940 + 430941.

It is an arithmetic number, because the mean of its divisors is an integer number (430941).

2⁸⁶¹⁸⁸¹ is an apocalyptic number.

It is an amenable number.

861881 is a deficient number, since it is larger than the sum of its proper divisors (1).

861881 is an equidigital number, since it uses as much as digits as its factorization.

861881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 32.

The square root of 861881 is about 928.3754628382. The cubic root of 861881 is about 95.1661358852.

The spelling of 861881 in words is "eight hundred sixty-one thousand, eight hundred eighty-one".