638791646 has 4 divisors (see below), whose sum is σ = 958187472. Its totient is φ = 319395822.

The previous prime is 638791633. The next prime is 638791649. The reversal of 638791646 is 646197836.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 638791594 and 638791603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638791649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159697910 + ... + 159697913.

It is an arithmetic number, because the mean of its divisors is an integer number (239546868).

Almost surely, 2^638791646 is an apocalyptic number.

638791646 is a deficient number, since it is larger than the sum of its proper divisors (319395826).

638791646 is a wasteful number, since it uses less digits than its factorization.

638791646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319395825.

The product of its digits is 1306368, while the sum is 50.

The square root of 638791646 is about 25274.3278051069. The cubic root of 638791646 is about 861.2311760340.

The spelling of 638791646 in words is "six hundred thirty-eight million, seven hundred ninety-one thousand, six hundred forty-six".