129828921 has 4 divisors (see below), whose sum is σ = 173105232. Its totient is φ = 86552612.

The previous prime is 129828901. The next prime is 129828929.

129828921 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 129828921 - 2⁷ = 129828793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (129828929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21638151 + ... + 21638156.

It is an arithmetic number, because the mean of its divisors is an integer number (43276308).

Almost surely, 2^129828921 is an apocalyptic number.

It is an amenable number.

129828921 is a deficient number, since it is larger than the sum of its proper divisors (43276311).

129828921 is an equidigital number, since it uses as much as digits as its factorization.

129828921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43276310.

The product of its digits is 41472, while the sum is 42.

The square root of 129828921 is about 11394.2494706760. The cubic root of 129828921 is about 506.3573860292.

The spelling of 129828921 in words is "one hundred twenty-nine million, eight hundred twenty-eight thousand, nine hundred twenty-one".