638649 has 12 divisors (see below), whose sum is σ = 1006512. Its totient is φ = 387000.

The previous prime is 638633. The next prime is 638663. The reversal of 638649 is 946836.

638649 is a `hidden beast` number, since 6 + 3 + 8 + 649 = 666.

638649 is nontrivially palindromic in base 16.

It is not a de Polignac number, because 638649 - 2⁴ = 638633 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638629) 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 11 ways as a sum of consecutive naturals, for example, 3127 + ... + 3324.

It is an arithmetic number, because the mean of its divisors is an integer number (83876).

2⁶³⁸⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

638649 is a deficient number, since it is larger than the sum of its proper divisors (367863).

638649 is a wasteful number, since it uses less digits than its factorization.

638649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6468 (or 6465 counting only the distinct ones).

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

The square root of 638649 is about 799.1551789233. The cubic root of 638649 is about 86.1167065235.

The spelling of 638649 in words is "six hundred thirty-eight thousand, six hundred forty-nine".