648021 has 16 divisors (see below), whose sum is σ = 959040. Its totient is φ = 385920.

The previous prime is 648019. The next prime is 648029. The reversal of 648021 is 120846.

It is not a de Polignac number, because 648021 - 2¹ = 648019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (648029) 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 15 ways as a sum of consecutive naturals, for example, 2275 + ... + 2543.

It is an arithmetic number, because the mean of its divisors is an integer number (59940).

648021 is a Friedman number, since it can be written as (806-1)^2-4, using all its digits and the basic arithmetic operations.

2⁶⁴⁸⁰²¹ is an apocalyptic number.

It is an amenable number.

648021 is a deficient number, since it is larger than the sum of its proper divisors (311019).

648021 is a wasteful number, since it uses less digits than its factorization.

648021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356.

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

The square root of 648021 is about 804.9975155241. The cubic root of 648021 is about 86.5359089997.

Adding to 648021 its reverse (120846), we get a palindrome (768867).

The spelling of 648021 in words is "six hundred forty-eight thousand, twenty-one".