129909921 has 8 divisors (see below), whose sum is σ = 173423040. Its totient is φ = 86501712.

The previous prime is 129909919. The next prime is 129909961.

129909921 is nontrivially palindromic in base 10.

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

It is not a de Polignac number, because 129909921 - 2¹ = 129909919 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (129909961) 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, 23290 + ... + 28323.

It is an arithmetic number, because the mean of its divisors is an integer number (21677880).

Almost surely, 2^129909921 is an apocalyptic number.

It is an amenable number.

129909921 is a deficient number, since it is larger than the sum of its proper divisors (43513119).

129909921 is an equidigital number, since it uses as much as digits as its factorization.

129909921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52455.

The product of its (nonzero) digits is 26244, while the sum is 42.

The square root of 129909921 is about 11397.8033409951. The cubic root of 129909921 is about 506.4626692517.

The spelling of 129909921 in words is "one hundred twenty-nine million, nine hundred nine thousand, nine hundred twenty-one".