128538931 has 2 divisors, whose sum is σ = 128538932. Its totient is φ = 128538930.

The previous prime is 128538929. The next prime is 128538941. The reversal of 128538931 is 139835821.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 128538931 - 2¹ = 128538929 is a prime.

It is a super-2 number, since 2×128538931² = 33044513565245522, which contains 22 as substring.

Together with 128538929, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (128538941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64269465 + 64269466.

It is an arithmetic number, because the mean of its divisors is an integer number (64269466).

Almost surely, 2^128538931 is an apocalyptic number.

128538931 is a deficient number, since it is larger than the sum of its proper divisors (1).

128538931 is an equidigital number, since it uses as much as digits as its factorization.

128538931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 40.

The square root of 128538931 is about 11337.5010915104. The cubic root of 128538931 is about 504.6747322141.

The spelling of 128538931 in words is "one hundred twenty-eight million, five hundred thirty-eight thousand, nine hundred thirty-one".