129963721 has 4 divisors (see below), whose sum is σ = 133476292. Its totient is φ = 126451152.

The previous prime is 129963697. The next prime is 129963739. The reversal of 129963721 is 127369921.

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 115863696 + 14100025 = 10764^2 + 3755^2 .

It is a cyclic number.

It is not a de Polignac number, because 129963721 - 2⁵ = 129963689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129363721) 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, 1756230 + ... + 1756303.

It is an arithmetic number, because the mean of its divisors is an integer number (33369073).

Almost surely, 2^129963721 is an apocalyptic number.

It is an amenable number.

129963721 is a deficient number, since it is larger than the sum of its proper divisors (3512571).

129963721 is an equidigital number, since it uses as much as digits as its factorization.

129963721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3512570.

The product of its digits is 40824, while the sum is 40.

The square root of 129963721 is about 11400.1632005862. The cubic root of 129963721 is about 506.5325739232.

It can be divided in two parts, 12996 and 3721, that multiplied together give a square (48358116 = 6954²).

The spelling of 129963721 in words is "one hundred twenty-nine million, nine hundred sixty-three thousand, seven hundred twenty-one".