129721826 has 8 divisors (see below), whose sum is σ = 209550684. Its totient is φ = 59871600.

The previous prime is 129721819. The next prime is 129721829. The reversal of 129721826 is 628127921.

It can be written as a sum of positive squares in 2 ways, for example, as 128029225 + 1692601 = 11315^2 + 1301^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 129721826.

It is not an unprimeable number, because it can be changed into a prime (129721829) 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, 2494625 + ... + 2494676.

Almost surely, 2^129721826 is an apocalyptic number.

129721826 is a deficient number, since it is larger than the sum of its proper divisors (79828858).

129721826 is a wasteful number, since it uses less digits than its factorization.

129721826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4989316.

The product of its digits is 24192, while the sum is 38.

The square root of 129721826 is about 11389.5489814127. The cubic root of 129721826 is about 506.2181174658.

The spelling of 129721826 in words is "one hundred twenty-nine million, seven hundred twenty-one thousand, eight hundred twenty-six".