649638 has 48 divisors (see below), whose sum is σ = 1634256. Its totient is φ = 184320.

The previous prime is 649633. The next prime is 649639. The reversal of 649638 is 836946.

649638 is a `hidden beast` number, since 649 + 6 + 3 + 8 = 666.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649631) 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 23 ways as a sum of consecutive naturals, for example, 3270 + ... + 3462.

It is an arithmetic number, because the mean of its divisors is an integer number (34047).

649638 is a Friedman number, since it can be written as 9843*66, using all its digits and the basic arithmetic operations.

2⁶⁴⁹⁶³⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 649638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (817128).

649638 is an abundant number, since it is smaller than the sum of its proper divisors (984618).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

649638 is a wasteful number, since it uses less digits than its factorization.

649638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229 (or 226 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 649638 is about 806.0012406938. The cubic root of 649638 is about 86.6078265963.

The spelling of 649638 in words is "six hundred forty-nine thousand, six hundred thirty-eight".