991000000129 has 2 divisors, whose sum is σ = 991000000130. Its totient is φ = 991000000128.

The previous prime is 991000000073. The next prime is 991000000139. The reversal of 991000000129 is 921000000199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 928987545600 + 62012454529 = 963840^2 + 249023^2 .

It is a cyclic number.

It is not a de Polignac number, because 991000000129 - 2²⁹ = 990463129217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991000000129.

It is not a weakly prime, because it can be changed into another prime (991000000139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495500000064 + 495500000065.

It is an arithmetic number, because the mean of its divisors is an integer number (495500000065).

Almost surely, 2^991000000129 is an apocalyptic number.

It is an amenable number.

991000000129 is a deficient number, since it is larger than the sum of its proper divisors (1).

991000000129 is an equidigital number, since it uses as much as digits as its factorization.

991000000129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 31.

The spelling of 991000000129 in words is "nine hundred ninety-one billion, one hundred twenty-nine", and thus it is an aban number.