861001 has 2 divisors, whose sum is σ = 861002. Its totient is φ = 861000.

The previous prime is 860971. The next prime is 861013. The reversal of 861001 is 100168.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 853776 + 7225 = 924^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 861001 - 2⁵ = 860969 is a prime.

It is not a weakly prime, because it can be changed into another prime (861031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430500 + 430501.

It is an arithmetic number, because the mean of its divisors is an integer number (430501).

2⁸⁶¹⁰⁰¹ is an apocalyptic number.

It is an amenable number.

861001 is a deficient number, since it is larger than the sum of its proper divisors (1).

861001 is an equidigital number, since it uses as much as digits as its factorization.

861001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 861001 is about 927.9013956235. The cubic root of 861001 is about 95.1337359297.

Adding to 861001 its reverse (100168), we get a palindrome (961169).

It can be divided in two parts, 8 and 61001, that added together give a square (61009 = 247²).

The spelling of 861001 in words is "eight hundred sixty-one thousand, one".