128987197421 has 2 divisors, whose sum is σ = 128987197422. Its totient is φ = 128987197420.

The previous prime is 128987197403. The next prime is 128987197429. The reversal of 128987197421 is 124791789821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127388317225 + 1598880196 = 356915^2 + 39986^2 .

It is a cyclic number.

It is not a de Polignac number, because 128987197421 - 2³⁰ = 127913455597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128987197429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64493598710 + 64493598711.

It is an arithmetic number, because the mean of its divisors is an integer number (64493598711).

Almost surely, 2^128987197421 is an apocalyptic number.

It is an amenable number.

128987197421 is a deficient number, since it is larger than the sum of its proper divisors (1).

128987197421 is an equidigital number, since it uses as much as digits as its factorization.

128987197421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4064256, while the sum is 59.

The spelling of 128987197421 in words is "one hundred twenty-eight billion, nine hundred eighty-seven million, one hundred ninety-seven thousand, four hundred twenty-one".