129580721 has 4 divisors (see below), whose sum is σ = 129648372. Its totient is φ = 129513072.

The previous prime is 129580699. The next prime is 129580723. The reversal of 129580721 is 127085921.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 23902321 + 105678400 = 4889^2 + 10280^2 .

It is a cyclic number.

It is not a de Polignac number, because 129580721 - 2⁶ = 129580657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129580723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30866 + ... + 34811.

It is an arithmetic number, because the mean of its divisors is an integer number (32412093).

Almost surely, 2^129580721 is an apocalyptic number.

It is an amenable number.

129580721 is a deficient number, since it is larger than the sum of its proper divisors (67651).

129580721 is an equidigital number, since it uses as much as digits as its factorization.

129580721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67650.

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 129580721 is about 11383.3528013499. The cubic root of 129580721 is about 506.0345045133.

The spelling of 129580721 in words is "one hundred twenty-nine million, five hundred eighty thousand, seven hundred twenty-one".