128391121820 has 36 divisors (see below), whose sum is σ = 291956860440. Its totient is φ = 47405951424.

The previous prime is 128391121811. The next prime is 128391121891. The reversal of 128391121820 is 28121193821.

It is a super-2 number, since 2×128391121820² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18989390 + ... + 18996149.

It is an arithmetic number, because the mean of its divisors is an integer number (8109912790).

Almost surely, 2^128391121820 is an apocalyptic number.

128391121820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128391121820 is an abundant number, since it is smaller than the sum of its proper divisors (163565738620).

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

128391121820 is a wasteful number, since it uses less digits than its factorization.

128391121820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37985574 (or 37985559 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 38.

The spelling of 128391121820 in words is "one hundred twenty-eight billion, three hundred ninety-one million, one hundred twenty-one thousand, eight hundred twenty".