638646836 has 48 divisors (see below), whose sum is σ = 1169931840. Its totient is φ = 304819200.

The previous prime is 638646821. The next prime is 638646839.

638646836 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×638646836² = 815739562265621792, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638646839) 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 15 ways as a sum of consecutive naturals, for example, 1684895 + ... + 1685273.

It is an arithmetic number, because the mean of its divisors is an integer number (24373580).

Almost surely, 2^638646836 is an apocalyptic number.

It is an amenable number.

638646836 is a deficient number, since it is larger than the sum of its proper divisors (531285004).

638646836 is a wasteful number, since it uses less digits than its factorization.

638646836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624 (or 622 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 50.

The square root of 638646836 is about 25271.4628781161. The cubic root of 638646836 is about 861.1660925739.

The spelling of 638646836 in words is "six hundred thirty-eight million, six hundred forty-six thousand, eight hundred thirty-six".