1638820068 has 12 divisors (see below), whose sum is σ = 3823913520. Its totient is φ = 546273352.

The previous prime is 1638820039. The next prime is 1638820069. The reversal of 1638820068 is 8600288361.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (1638820069) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68284158 + ... + 68284181.

It is an arithmetic number, because the mean of its divisors is an integer number (318659460).

Almost surely, 2^1638820068 is an apocalyptic number.

It is an amenable number.

1638820068 is an abundant number, since it is smaller than the sum of its proper divisors (2185093452).

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

1638820068 is a wasteful number, since it uses less digits than its factorization.

1638820068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136568346 (or 136568344 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 42.

The square root of 1638820068 is about 40482.3426693664. The cubic root of 1638820068 is about 1178.9908225014.

The spelling of 1638820068 in words is "one billion, six hundred thirty-eight million, eight hundred twenty thousand, sixty-eight".