129723109 has 2 divisors, whose sum is σ = 129723110. Its totient is φ = 129723108.

The previous prime is 129723091. The next prime is 129723137. The reversal of 129723109 is 901327921.

It is a happy number.

Together with previous prime (129723091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127464100 + 2259009 = 11290^2 + 1503^2 .

It is a cyclic number.

It is not a de Polignac number, because 129723109 - 2¹¹ = 129721061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129723179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64861554 + 64861555.

It is an arithmetic number, because the mean of its divisors is an integer number (64861555).

Almost surely, 2^129723109 is an apocalyptic number.

It is an amenable number.

129723109 is a deficient number, since it is larger than the sum of its proper divisors (1).

129723109 is an equidigital number, since it uses as much as digits as its factorization.

129723109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 129723109 is about 11389.6053048383. The cubic root of 129723109 is about 506.2197863592.

The spelling of 129723109 in words is "one hundred twenty-nine million, seven hundred twenty-three thousand, one hundred nine".