128421199889 has 2 divisors, whose sum is σ = 128421199890. Its totient is φ = 128421199888.

The previous prime is 128421199847. The next prime is 128421199897. The reversal of 128421199889 is 988991124821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 124354969600 + 4066230289 = 352640^2 + 63767^2 .

It is a cyclic number.

It is not a de Polignac number, because 128421199889 - 2²⁰ = 128420151313 is a prime.

It is a super-2 number, since 2×128421199889² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (128421199289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64210599944 + 64210599945.

It is an arithmetic number, because the mean of its divisors is an integer number (64210599945).

Almost surely, 2^128421199889 is an apocalyptic number.

It is an amenable number.

128421199889 is a deficient number, since it is larger than the sum of its proper divisors (1).

128421199889 is an equidigital number, since it uses as much as digits as its factorization.

128421199889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5971968, while the sum is 62.

The spelling of 128421199889 in words is "one hundred twenty-eight billion, four hundred twenty-one million, one hundred ninety-nine thousand, eight hundred eighty-nine".