129546721 has 4 divisors (see below), whose sum is σ = 130127872. Its totient is φ = 128965572.

The previous prime is 129546689. The next prime is 129546751. The reversal of 129546721 is 127645921.

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 129546721 - 2⁵ = 129546689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129546751) 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, 290241 + ... + 290686.

It is an arithmetic number, because the mean of its divisors is an integer number (32531968).

Almost surely, 2^129546721 is an apocalyptic number.

It is an amenable number.

129546721 is a deficient number, since it is larger than the sum of its proper divisors (581151).

129546721 is an equidigital number, since it uses as much as digits as its factorization.

129546721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581150.

The product of its digits is 30240, while the sum is 37.

The square root of 129546721 is about 11381.8592945090. The cubic root of 129546721 is about 505.9902420694.

The spelling of 129546721 in words is "one hundred twenty-nine million, five hundred forty-six thousand, seven hundred twenty-one".