128380729 has 4 divisors (see below), whose sum is σ = 128419876. Its totient is φ = 128341584.

The previous prime is 128380723. The next prime is 128380771. The reversal of 128380729 is 927083821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1863225 + 126517504 = 1365^2 + 11248^2 .

It is a cyclic number.

It is not a de Polignac number, because 128380729 - 2¹⁹ = 127856441 is a prime.

It is a super-2 number, since 2×128380729² = 32963223157142882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128380691 and 128380700.

It is not an unprimeable number, because it can be changed into a prime (128380723) 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, 14154 + ... + 21379.

It is an arithmetic number, because the mean of its divisors is an integer number (32104969).

Almost surely, 2^128380729 is an apocalyptic number.

It is an amenable number.

128380729 is a deficient number, since it is larger than the sum of its proper divisors (39147).

128380729 is an equidigital number, since it uses as much as digits as its factorization.

128380729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39146.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 128380729 is about 11330.5220091574. The cubic root of 128380729 is about 504.4676008573.

The spelling of 128380729 in words is "one hundred twenty-eight million, three hundred eighty thousand, seven hundred twenty-nine".