666863 has 4 divisors (see below), whose sum is σ = 668928.
Its totient is φ = 664800.
The previous prime is 666857. The next prime is 666871. The reversal of 666863 is 368666.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 368666 = 2 ⋅184333.
It is a cyclic number.
It is not a de Polignac number, because 666863 - 28 = 666607 is a prime.
It is a Duffinian number.
It is a plaindrome in base 9.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (666823) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 431 + ... + 1232.
It is an arithmetic number, because the mean of its divisors is an integer number (167232).
2666863 is an apocalyptic number.
666863 is the 437-th centered heptagonal number.
666863 is a deficient number, since it is larger than the sum of its proper divisors (2065).
666863 is a wasteful number, since it uses less digits than its factorization.
666863 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 2064.
The product of its digits is 31104, while the sum is 35.
The square root of 666863 is about 816.6168011987.
The cubic root of 666863 is about 87.3666212802.
The spelling of 666863 in words is "six hundred sixty-six thousand, eight hundred sixty-three".