864021 has 4 divisors (see below), whose sum is σ = 1152032. Its totient is φ = 576012.

The previous prime is 864013. The next prime is 864029. The reversal of 864021 is 120468.

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 an interprime number because it is at equal distance from previous prime (864013) and next prime (864029).

It is not a de Polignac number, because 864021 - 2³ = 864013 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (864029) 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, 144001 + ... + 144006.

It is an arithmetic number, because the mean of its divisors is an integer number (288008).

2⁸⁶⁴⁰²¹ is an apocalyptic number.

It is an amenable number.

864021 is a deficient number, since it is larger than the sum of its proper divisors (288011).

864021 is a wasteful number, since it uses less digits than its factorization.

864021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288010.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 864021 is about 929.5272992226. The cubic root of 864021 is about 95.2448347651.

Adding to 864021 its reverse (120468), we get a palindrome (984489).

The spelling of 864021 in words is "eight hundred sixty-four thousand, twenty-one".