648106821 has 24 divisors (see below), whose sum is σ = 946239840. Its totient is φ = 427440096.

The previous prime is 648106813. The next prime is 648106831. The reversal of 648106821 is 128601846.

648106821 is a `hidden beast` number, since 648 + 1 + 0 + 6 + 8 + 2 + 1 = 666.

It is not a de Polignac number, because 648106821 - 2³ = 648106813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (648106831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 433351 + ... + 434843.

It is an arithmetic number, because the mean of its divisors is an integer number (39426660).

Almost surely, 2^648106821 is an apocalyptic number.

It is an amenable number.

648106821 is a deficient number, since it is larger than the sum of its proper divisors (298133019).

648106821 is a wasteful number, since it uses less digits than its factorization.

648106821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1985 (or 1982 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 648106821 is about 25457.9421988502. The cubic root of 648106821 is about 865.3972897389.

It can be divided in two parts, 64810 and 6821, that added together give a triangular number (71631 = T₃₇₈).

The spelling of 648106821 in words is "six hundred forty-eight million, one hundred six thousand, eight hundred twenty-one".