4000861 has 2 divisors, whose sum is σ = 4000862. Its totient is φ = 4000860.

The previous prime is 4000853. The next prime is 4000879. The reversal of 4000861 is 1680004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2295225 + 1705636 = 1515^2 + 1306^2 .

It is a cyclic number.

It is not a de Polignac number, because 4000861 - 2³ = 4000853 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4000261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2000430 + 2000431.

It is an arithmetic number, because the mean of its divisors is an integer number (2000431).

Almost surely, 2^4000861 is an apocalyptic number.

It is an amenable number.

4000861 is a deficient number, since it is larger than the sum of its proper divisors (1).

4000861 is an equidigital number, since it uses as much as digits as its factorization.

4000861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 4000861 is about 2000.2152384181. The cubic root of 4000861 is about 158.7514939823.

Adding to 4000861 its reverse (1680004), we get a palindrome (5680865).

It can be divided in two parts, 4000 and 861, that multiplied together give a triangular number (3444000 = T₂₆₂₄).

The spelling of 4000861 in words is "four million, eight hundred sixty-one", and thus it is an aban number.