866421 has 6 divisors (see below), whose sum is σ = 1251510. Its totient is φ = 577608.

The previous prime is 866417. The next prime is 866431. The reversal of 866421 is 124668.

It can be written as a sum of positive squares in only one way, i.e., 864900 + 1521 = 930^2 + 39^2 .

It is not a de Polignac number, because 866421 - 2² = 866417 is a prime.

It is a plaindrome in base 13.

It is a nialpdrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 866421.

It is not an unprimeable number, because it can be changed into a prime (866431) 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 5 ways as a sum of consecutive naturals, for example, 48126 + ... + 48143.

It is an arithmetic number, because the mean of its divisors is an integer number (208585).

2⁸⁶⁶⁴²¹ is an apocalyptic number.

It is an amenable number.

866421 is a deficient number, since it is larger than the sum of its proper divisors (385089).

866421 is a wasteful number, since it uses less digits than its factorization.

866421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96275 (or 96272 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 866421 is about 930.8173827341. The cubic root of 866421 is about 95.3329407561.

The spelling of 866421 in words is "eight hundred sixty-six thousand, four hundred twenty-one".