1638861111389 has 8 divisors (see below), whose sum is σ = 1678915449792. Its totient is φ = 1598810683360.

The previous prime is 1638861111359. The next prime is 1638861111421. The reversal of 1638861111389 is 9831111688361.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1638861111389 - 2¹² = 1638861107293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638861111359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120059 + ... + 1814424.

It is an arithmetic number, because the mean of its divisors is an integer number (209864431224).

Almost surely, 2^{1638861111389} is an apocalyptic number.

It is an amenable number.

1638861111389 is a deficient number, since it is larger than the sum of its proper divisors (40054338403).

1638861111389 is a wasteful number, since it uses less digits than its factorization.

1638861111389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1955187.

The product of its digits is 1492992, while the sum is 56.

The spelling of 1638861111389 in words is "one trillion, six hundred thirty-eight billion, eight hundred sixty-one million, one hundred eleven thousand, three hundred eighty-nine".