128772815 has 4 divisors (see below), whose sum is σ = 154527384. Its totient is φ = 103018248.

The previous prime is 128772781. The next prime is 128772817. The reversal of 128772815 is 518277821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 518277821 = 29 ⋅17871649.

It is a cyclic number.

It is not a de Polignac number, because 128772815 - 2¹⁶ = 128707279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128772817) 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, 12877277 + ... + 12877286.

It is an arithmetic number, because the mean of its divisors is an integer number (38631846).

Almost surely, 2^128772815 is an apocalyptic number.

128772815 is a deficient number, since it is larger than the sum of its proper divisors (25754569).

128772815 is an equidigital number, since it uses as much as digits as its factorization.

128772815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25754568.

The product of its digits is 62720, while the sum is 41.

The square root of 128772815 is about 11347.8110223955. The cubic root of 128772815 is about 504.9806416786.

The spelling of 128772815 in words is "one hundred twenty-eight million, seven hundred seventy-two thousand, eight hundred fifteen".