129687581 has 2 divisors, whose sum is σ = 129687582. Its totient is φ = 129687580.

The previous prime is 129687557. The next prime is 129687589. The reversal of 129687581 is 185786921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 113081956 + 16605625 = 10634^2 + 4075^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129687581 is a prime.

It is a super-2 number, since 2×129687581² = 33637737331263122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129687589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64843790 + 64843791.

It is an arithmetic number, because the mean of its divisors is an integer number (64843791).

Almost surely, 2^129687581 is an apocalyptic number.

It is an amenable number.

129687581 is a deficient number, since it is larger than the sum of its proper divisors (1).

129687581 is an equidigital number, since it uses as much as digits as its factorization.

129687581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 47.

The square root of 129687581 is about 11388.0455302918. The cubic root of 129687581 is about 506.1735683830.

The spelling of 129687581 in words is "one hundred twenty-nine million, six hundred eighty-seven thousand, five hundred eighty-one".