128772121 has 2 divisors, whose sum is σ = 128772122. Its totient is φ = 128772120.

The previous prime is 128772079. The next prime is 128772157. The reversal of 128772121 is 121277821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 95824521 + 32947600 = 9789^2 + 5740^2 .

It is a cyclic number.

It is not a de Polignac number, because 128772121 - 2¹⁷ = 128641049 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (128772221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64386060 + 64386061.

It is an arithmetic number, because the mean of its divisors is an integer number (64386061).

Almost surely, 2^128772121 is an apocalyptic number.

It is an amenable number.

128772121 is a deficient number, since it is larger than the sum of its proper divisors (1).

128772121 is an equidigital number, since it uses as much as digits as its factorization.

128772121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3136, while the sum is 31.

The square root of 128772121 is about 11347.7804437696. The cubic root of 128772121 is about 504.9797345068.

The spelling of 128772121 in words is "one hundred twenty-eight million, seven hundred seventy-two thousand, one hundred twenty-one".