128956673 has 4 divisors (see below), whose sum is σ = 131700480. Its totient is φ = 126212868.

The previous prime is 128956643. The next prime is 128956687. The reversal of 128956673 is 376659821.

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: 376659821 = 839 ⋅448939.

It is a cyclic number.

It is not a de Polignac number, because 128956673 - 2⁶ = 128956609 is a prime.

It is a super-2 number, since 2×128956673² = 33259647022457858, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (47), and also a Moran number because the ratio is a prime number: 2743759 = 128956673 / (1 + 2 + 8 + 9 + 5 + 6 + 6 + 7 + 3).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128956643) 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, 1371833 + ... + 1371926.

It is an arithmetic number, because the mean of its divisors is an integer number (32925120).

Almost surely, 2^128956673 is an apocalyptic number.

It is an amenable number.

128956673 is a deficient number, since it is larger than the sum of its proper divisors (2743807).

128956673 is an equidigital number, since it uses as much as digits as its factorization.

128956673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2743806.

The product of its digits is 544320, while the sum is 47.

The square root of 128956673 is about 11355.9091665969. The cubic root of 128956673 is about 505.2208595094.

The spelling of 128956673 in words is "one hundred twenty-eight million, nine hundred fifty-six thousand, six hundred seventy-three".