866553 has 4 divisors (see below), whose sum is σ = 1155408. Its totient is φ = 577700.

The previous prime is 866519. The next prime is 866573. The reversal of 866553 is 355668.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866553 is a prime.

It is a D-number.

866553 is a lucky number.

It is a plaindrome in base 13.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (866513) 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, 144423 + ... + 144428.

It is an arithmetic number, because the mean of its divisors is an integer number (288852).

2⁸⁶⁶⁵⁵³ is an apocalyptic number.

It is an amenable number.

866553 is a deficient number, since it is larger than the sum of its proper divisors (288855).

866553 is a wasteful number, since it uses less digits than its factorization.

866553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288854.

The product of its digits is 21600, while the sum is 33.

The square root of 866553 is about 930.8882854564. Note that the first 3 decimals coincide. The cubic root of 866553 is about 95.3377818627.

Adding to 866553 its sum of digits (33), we get a triangular number (866586 = T₁₃₁₆).

Adding to 866553 its reverse (355668), we get a palindrome (1222221).

The spelling of 866553 in words is "eight hundred sixty-six thousand, five hundred fifty-three".