648821 has 4 divisors (see below), whose sum is σ = 651552. Its totient is φ = 646092.

The previous prime is 648803. The next prime is 648841. The reversal of 648821 is 128846.

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 not a de Polignac number, because 648821 - 2¹⁸ = 386677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (648841) 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, 971 + ... + 1496.

It is an arithmetic number, because the mean of its divisors is an integer number (162888).

2⁶⁴⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

648821 is a deficient number, since it is larger than the sum of its proper divisors (2731).

648821 is a wasteful number, since it uses less digits than its factorization.

648821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2730.

The product of its digits is 3072, while the sum is 29.

The square root of 648821 is about 805.4942582042. The cubic root of 648821 is about 86.5715046869.

The spelling of 648821 in words is "six hundred forty-eight thousand, eight hundred twenty-one".