129839721 has 8 divisors (see below), whose sum is σ = 188857824. Its totient is φ = 78690720.

The previous prime is 129839719. The next prime is 129839729. The reversal of 129839721 is 127938921.

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

It is not a de Polignac number, because 129839721 - 2¹ = 129839719 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (129839729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1967236 + ... + 1967301.

It is an arithmetic number, because the mean of its divisors is an integer number (23607228).

Almost surely, 2^129839721 is an apocalyptic number.

129839721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

129839721 is a deficient number, since it is larger than the sum of its proper divisors (59018103).

129839721 is a wasteful number, since it uses less digits than its factorization.

129839721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3934551.

The product of its digits is 54432, while the sum is 42.

The square root of 129839721 is about 11394.7233840932. The cubic root of 129839721 is about 506.3714263219.

The spelling of 129839721 in words is "one hundred twenty-nine million, eight hundred thirty-nine thousand, seven hundred twenty-one".