129811909 has 2 divisors, whose sum is σ = 129811910. Its totient is φ = 129811908.

The previous prime is 129811841. The next prime is 129811943. The reversal of 129811909 is 909118921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 110187009 + 19624900 = 10497^2 + 4430^2 .

It is an emirp because it is prime and its reverse (909118921) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129811909 is a prime.

It is a super-2 number, since 2×129811909² = 33702263436448562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129815909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64905954 + 64905955.

It is an arithmetic number, because the mean of its divisors is an integer number (64905955).

Almost surely, 2^129811909 is an apocalyptic number.

It is an amenable number.

129811909 is a deficient number, since it is larger than the sum of its proper divisors (1).

129811909 is an equidigital number, since it uses as much as digits as its factorization.

129811909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 40.

The square root of 129811909 is about 11393.5029293014. The cubic root of 129811909 is about 506.3352683889.

The spelling of 129811909 in words is "one hundred twenty-nine million, eight hundred eleven thousand, nine hundred nine".