865643 has 2 divisors, whose sum is σ = 865644. Its totient is φ = 865642.

The previous prime is 865639. The next prime is 865661. The reversal of 865643 is 346568.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 865643 - 2² = 865639 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (865043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432821 + 432822.

It is an arithmetic number, because the mean of its divisors is an integer number (432822).

2⁸⁶⁵⁶⁴³ is an apocalyptic number.

865643 is a deficient number, since it is larger than the sum of its proper divisors (1).

865643 is an equidigital number, since it uses as much as digits as its factorization.

865643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 32.

The square root of 865643 is about 930.3993766120. The cubic root of 865643 is about 95.3043975734.

The spelling of 865643 in words is "eight hundred sixty-five thousand, six hundred forty-three".