1920817138878 has 160 divisors (see below), whose sum is σ = 4717180527840. Its totient is φ = 579363840000.

The previous prime is 1920817138873. The next prime is 1920817138879. The reversal of 1920817138878 is 8788317180291.

1920817138878 is a `hidden beast` number, since 19 + 2 + 0 + 8 + 171 + 388 + 78 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1920817138873) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 363719598 + ... + 363724878.

It is an arithmetic number, because the mean of its divisors is an integer number (29482378299).

Almost surely, 2^{1920817138878} is an apocalyptic number.

1920817138878 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1920817138878, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2358590263920).

1920817138878 is an abundant number, since it is smaller than the sum of its proper divisors (2796363388962).

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

1920817138878 is a wasteful number, since it uses less digits than its factorization.

1920817138878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6216 (or 6207 counting only the distinct ones).

The product of its (nonzero) digits is 10838016, while the sum is 63.

The spelling of 1920817138878 in words is "one trillion, nine hundred twenty billion, eight hundred seventeen million, one hundred thirty-eight thousand, eight hundred seventy-eight".