648865021 has 16 divisors (see below), whose sum is σ = 749167744. Its totient is φ = 550494144.

The previous prime is 648864989. The next prime is 648865037. The reversal of 648865021 is 120568846.

It is a cyclic number.

It is not a de Polignac number, because 648865021 - 2⁵ = 648864989 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 (648865621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 315031 + ... + 317083.

It is an arithmetic number, because the mean of its divisors is an integer number (46822984).

Almost surely, 2^648865021 is an apocalyptic number.

It is an amenable number.

648865021 is a deficient number, since it is larger than the sum of its proper divisors (100302723).

648865021 is a wasteful number, since it uses less digits than its factorization.

648865021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2500.

The product of its (nonzero) digits is 92160, while the sum is 40.

The square root of 648865021 is about 25472.8290733479. The cubic root of 648865021 is about 865.7346253460.

The spelling of 648865021 in words is "six hundred forty-eight million, eight hundred sixty-five thousand, twenty-one".