1638126813 has 8 divisors (see below), whose sum is σ = 2184527488. Its totient is φ = 1091905344.

The previous prime is 1638126803. The next prime is 1638126821. The reversal of 1638126813 is 3186218361.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1638126813 - 2¹⁷ = 1637995741 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 (1638126803) 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 in 7 ways as a sum of consecutive naturals, for example, 21781 + ... + 61242.

It is an arithmetic number, because the mean of its divisors is an integer number (273065936).

Almost surely, 2^1638126813 is an apocalyptic number.

It is an amenable number.

1638126813 is a deficient number, since it is larger than the sum of its proper divisors (546400675).

1638126813 is an equidigital number, since it uses as much as digits as its factorization.

1638126813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89603.

The product of its digits is 41472, while the sum is 39.

The square root of 1638126813 is about 40473.7793268679. The cubic root of 1638126813 is about 1178.8245531681.

The spelling of 1638126813 in words is "one billion, six hundred thirty-eight million, one hundred twenty-six thousand, eight hundred thirteen".