129561391 has 2 divisors, whose sum is σ = 129561392. Its totient is φ = 129561390.

The previous prime is 129561389. The next prime is 129561407. The reversal of 129561391 is 193165921.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 129561391 - 2¹ = 129561389 is a prime.

Together with 129561389, it forms a pair of twin primes.

It is equal to p_7354783 and since 129561391 and 7354783 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 129561391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129561191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64780695 + 64780696.

It is an arithmetic number, because the mean of its divisors is an integer number (64780696).

Almost surely, 2^129561391 is an apocalyptic number.

129561391 is a deficient number, since it is larger than the sum of its proper divisors (1).

129561391 is an equidigital number, since it uses as much as digits as its factorization.

129561391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14580, while the sum is 37.

The square root of 129561391 is about 11382.5037228195. The cubic root of 129561391 is about 506.0093409619.

The spelling of 129561391 in words is "one hundred twenty-nine million, five hundred sixty-one thousand, three hundred ninety-one".