128644531 has 2 divisors, whose sum is σ = 128644532. Its totient is φ = 128644530.

The previous prime is 128644487. The next prime is 128644561. The reversal of 128644531 is 135446821.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 128644531 - 2¹⁹ = 128120243 is a prime.

It is a super-2 number, since 2×128644531² = 33098830712419922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (128644561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64322265 + 64322266.

It is an arithmetic number, because the mean of its divisors is an integer number (64322266).

Almost surely, 2^128644531 is an apocalyptic number.

128644531 is a deficient number, since it is larger than the sum of its proper divisors (1).

128644531 is an equidigital number, since it uses as much as digits as its factorization.

128644531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23040, while the sum is 34.

The square root of 128644531 is about 11342.1572463090. The cubic root of 128644531 is about 504.8128980436.

The spelling of 128644531 in words is "one hundred twenty-eight million, six hundred forty-four thousand, five hundred thirty-one".