129435781 has 2 divisors, whose sum is σ = 129435782. Its totient is φ = 129435780.

The previous prime is 129435763. The next prime is 129435797. The reversal of 129435781 is 187534921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 123988225 + 5447556 = 11135^2 + 2334^2 .

It is a cyclic number.

It is not a de Polignac number, because 129435781 - 2¹⁵ = 129403013 is a prime.

It is a super-2 number, since 2×129435781² = 33507242806159922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129435721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64717890 + 64717891.

It is an arithmetic number, because the mean of its divisors is an integer number (64717891).

Almost surely, 2^129435781 is an apocalyptic number.

It is an amenable number.

129435781 is a deficient number, since it is larger than the sum of its proper divisors (1).

129435781 is an equidigital number, since it uses as much as digits as its factorization.

129435781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 40.

The square root of 129435781 is about 11376.9847059755. The cubic root of 129435781 is about 505.8457624340.

The spelling of 129435781 in words is "one hundred twenty-nine million, four hundred thirty-five thousand, seven hundred eighty-one".