129799921 has 2 divisors, whose sum is σ = 129799922. Its totient is φ = 129799920.

The previous prime is 129799867. The next prime is 129799993. The reversal of 129799921 is 129997921.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120121600 + 9678321 = 10960^2 + 3111^2 .

It is a cyclic number.

It is not a de Polignac number, because 129799921 - 2⁹ = 129799409 is a prime.

It is not a weakly prime, because it can be changed into another prime (129799121) 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 as a sum of consecutive naturals, namely, 64899960 + 64899961.

It is an arithmetic number, because the mean of its divisors is an integer number (64899961).

Almost surely, 2^129799921 is an apocalyptic number.

It is an amenable number.

129799921 is a deficient number, since it is larger than the sum of its proper divisors (1).

129799921 is an equidigital number, since it uses as much as digits as its factorization.

129799921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 183708, while the sum is 49.

The square root of 129799921 is about 11392.9768278532. The cubic root of 129799921 is about 506.3196813905.

The spelling of 129799921 in words is "one hundred twenty-nine million, seven hundred ninety-nine thousand, nine hundred twenty-one".