129728249 has 4 divisors (see below), whose sum is σ = 148260864. Its totient is φ = 111195636.

The previous prime is 129728201. The next prime is 129728279. The reversal of 129728249 is 942827921.

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, and also an emirpimes, since its reverse is a distinct semiprime: 942827921 = 7 ⋅134689703.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129728249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129728279) 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, 9266297 + ... + 9266310.

It is an arithmetic number, because the mean of its divisors is an integer number (37065216).

Almost surely, 2^129728249 is an apocalyptic number.

It is an amenable number.

129728249 is a deficient number, since it is larger than the sum of its proper divisors (18532615).

129728249 is an equidigital number, since it uses as much as digits as its factorization.

129728249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18532614.

The product of its digits is 145152, while the sum is 44.

The square root of 129728249 is about 11389.8309469456. The cubic root of 129728249 is about 506.2264722287.

The spelling of 129728249 in words is "one hundred twenty-nine million, seven hundred twenty-eight thousand, two hundred forty-nine".