861643 has 4 divisors (see below), whose sum is σ = 863968. Its totient is φ = 859320.

The previous prime is 861617. The next prime is 861647. The reversal of 861643 is 346168.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 861643 - 2⁹ = 861131 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (861647) 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 in 3 ways as a sum of consecutive naturals, for example, 468 + ... + 1393.

It is an arithmetic number, because the mean of its divisors is an integer number (215992).

2⁸⁶¹⁶⁴³ is an apocalyptic number.

861643 is a deficient number, since it is larger than the sum of its proper divisors (2325).

861643 is a wasteful number, since it uses less digits than its factorization.

861643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2324.

The product of its digits is 3456, while the sum is 28.

The square root of 861643 is about 928.2472730905. The cubic root of 861643 is about 95.1573753465.

The spelling of 861643 in words is "eight hundred sixty-one thousand, six hundred forty-three".