1638939168 has 36 divisors (see below), whose sum is σ = 4660734078. Its totient is φ = 546312960.

The previous prime is 1638939167. The next prime is 1638939173. The reversal of 1638939168 is 8619398361.

It can be written as a sum of positive squares in only one way, i.e., 1557723024 + 81216144 = 39468^2 + 9012^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×1638939168² = 5372243192809064448, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1638939163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2845093 + ... + 2845668.

Almost surely, 2^1638939168 is an apocalyptic number.

1638939168 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1638939168 is an abundant number, since it is smaller than the sum of its proper divisors (3021794910).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1638939168 is a wasteful number, since it uses less digits than its factorization.

1638939168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5690777 (or 5690766 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 54.

The square root of 1638939168 is about 40483.8136543483. The cubic root of 1638939168 is about 1179.0193825629.

The spelling of 1638939168 in words is "one billion, six hundred thirty-eight million, nine hundred thirty-nine thousand, one hundred sixty-eight".