129999638 has 4 divisors (see below), whose sum is σ = 194999460. Its totient is φ = 64999818.

The previous prime is 129999637. The next prime is 129999673. The reversal of 129999638 is 836999921.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129999637) 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, 32499908 + ... + 32499911.

It is an arithmetic number, because the mean of its divisors is an integer number (48749865).

Almost surely, 2^129999638 is an apocalyptic number.

129999638 is a deficient number, since it is larger than the sum of its proper divisors (64999822).

129999638 is an equidigital number, since it uses as much as digits as its factorization.

129999638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64999821.

The product of its digits is 1889568, while the sum is 56.

The square root of 129999638 is about 11401.7383762302. The cubic root of 129999638 is about 506.5792316998.

The spelling of 129999638 in words is "one hundred twenty-nine million, nine hundred ninety-nine thousand, six hundred thirty-eight".