129696781 has 2 divisors, whose sum is σ = 129696782. Its totient is φ = 129696780.

The previous prime is 129696751. The next prime is 129696799. The reversal of 129696781 is 187696921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 115218756 + 14478025 = 10734^2 + 3805^2 .

It is an emirp because it is prime and its reverse (187696921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 129696781 - 2¹⁵ = 129664013 is a prime.

It is a super-2 number, since 2×129696781² = 33642510003523922, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129696731) 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, 64848390 + 64848391.

It is an arithmetic number, because the mean of its divisors is an integer number (64848391).

Almost surely, 2^129696781 is an apocalyptic number.

It is an amenable number.

129696781 is a deficient number, since it is larger than the sum of its proper divisors (1).

129696781 is an equidigital number, since it uses as much as digits as its factorization.

129696781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 49.

The square root of 129696781 is about 11388.4494554790. The cubic root of 129696781 is about 506.1855373695.

The spelling of 129696781 in words is "one hundred twenty-nine million, six hundred ninety-six thousand, seven hundred eighty-one".