128560021 has 2 divisors, whose sum is σ = 128560022. Its totient is φ = 128560020.

The previous prime is 128560013. The next prime is 128560037. The reversal of 128560021 is 120065821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83064996 + 45495025 = 9114^2 + 6745^2 .

It is a cyclic number.

It is not a de Polignac number, because 128560021 - 2³ = 128560013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128560121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64280010 + 64280011.

It is an arithmetic number, because the mean of its divisors is an integer number (64280011).

Almost surely, 2^128560021 is an apocalyptic number.

It is an amenable number.

128560021 is a deficient number, since it is larger than the sum of its proper divisors (1).

128560021 is an equidigital number, since it uses as much as digits as its factorization.

128560021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 128560021 is about 11338.4311525008. The cubic root of 128560021 is about 504.7023321741.

The spelling of 128560021 in words is "one hundred twenty-eight million, five hundred sixty thousand, twenty-one".