129306781 has 2 divisors, whose sum is σ = 129306782. Its totient is φ = 129306780.

The previous prime is 129306757. The next prime is 129306787. The reversal of 129306781 is 187603921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 118613881 + 10692900 = 10891^2 + 3270^2 .

It is a cyclic number.

It is not a de Polignac number, because 129306781 - 2²³ = 120918173 is a prime.

It is a super-2 number, since 2×129306781² = 33440487225163922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 129306781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129306787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64653390 + 64653391.

It is an arithmetic number, because the mean of its divisors is an integer number (64653391).

Almost surely, 2^129306781 is an apocalyptic number.

It is an amenable number.

129306781 is a deficient number, since it is larger than the sum of its proper divisors (1).

129306781 is an equidigital number, since it uses as much as digits as its factorization.

129306781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 129306781 is about 11371.3139522221. The cubic root of 129306781 is about 505.6776590110.

The spelling of 129306781 in words is "one hundred twenty-nine million, three hundred six thousand, seven hundred eighty-one".