129128491 has 2 divisors, whose sum is σ = 129128492. Its totient is φ = 129128490.

The previous prime is 129128479. The next prime is 129128507. The reversal of 129128491 is 194821921.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129128491 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 129128491.

It is not a weakly prime, because it can be changed into another prime (129128401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64564245 + 64564246.

It is an arithmetic number, because the mean of its divisors is an integer number (64564246).

Almost surely, 2^129128491 is an apocalyptic number.

129128491 is a deficient number, since it is larger than the sum of its proper divisors (1).

129128491 is an equidigital number, since it uses as much as digits as its factorization.

129128491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 37.

The square root of 129128491 is about 11363.4717846264. The cubic root of 129128491 is about 505.4451402996.

The spelling of 129128491 in words is "one hundred twenty-nine million, one hundred twenty-eight thousand, four hundred ninety-one".