638885785 has 4 divisors (see below), whose sum is σ = 766662948. Its totient is φ = 511108624.

The previous prime is 638885759. The next prime is 638885791. The reversal of 638885785 is 587588836.

638885785 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 333719824 + 305165961 = 18268^2 + 17469^2 .

It is a cyclic number.

It is not a de Polignac number, because 638885785 - 2¹³ = 638877593 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63888574 + ... + 63888583.

It is an arithmetic number, because the mean of its divisors is an integer number (191665737).

Almost surely, 2^638885785 is an apocalyptic number.

It is an amenable number.

638885785 is a deficient number, since it is larger than the sum of its proper divisors (127777163).

638885785 is a wasteful number, since it uses less digits than its factorization.

638885785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127777162.

The product of its digits is 12902400, while the sum is 58.

The square root of 638885785 is about 25276.1900807855. The cubic root of 638885785 is about 861.2734806257.

The spelling of 638885785 in words is "six hundred thirty-eight million, eight hundred eighty-five thousand, seven hundred eighty-five".