128997799821 has 12 divisors (see below), whose sum is σ = 203269260480. Its totient is φ = 78180484680.

The previous prime is 128997799817. The next prime is 128997799823.

128997799821 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 128997799821 - 2² = 128997799817 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128997799821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128997799823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 651503941 + ... + 651504138.

It is an arithmetic number, because the mean of its divisors is an integer number (16939105040).

Almost surely, 2^128997799821 is an apocalyptic number.

128997799821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128997799821 is a deficient number, since it is larger than the sum of its proper divisors (74271460659).

128997799821 is a wasteful number, since it uses less digits than its factorization.

128997799821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1303008096 (or 1303008093 counting only the distinct ones).

The product of its digits is 82301184, while the sum is 72.

The spelling of 128997799821 in words is "one hundred twenty-eight billion, nine hundred ninety-seven million, seven hundred ninety-nine thousand, eight hundred twenty-one".