861663 has 8 divisors (see below), whose sum is σ = 1253376. Its totient is φ = 522200.

The previous prime is 861659. The next prime is 861691. The reversal of 861663 is 366168.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 861663 - 2² = 861659 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 861663.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13023 + ... + 13088.

It is an arithmetic number, because the mean of its divisors is an integer number (156672).

2⁸⁶¹⁶⁶³ is an apocalyptic number.

861663 is a deficient number, since it is larger than the sum of its proper divisors (391713).

861663 is a wasteful number, since it uses less digits than its factorization.

861663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26125.

The product of its digits is 5184, while the sum is 30.

The square root of 861663 is about 928.2580460195. The cubic root of 861663 is about 95.1581115883.

The spelling of 861663 in words is "eight hundred sixty-one thousand, six hundred sixty-three".