128312505 has 24 divisors (see below), whose sum is σ = 230647872. Its totient is φ = 68432688.

The previous prime is 128312477. The next prime is 128312507. The reversal of 128312505 is 505213821.

It is a happy number.

128312505 is a `hidden beast` number, since 128 + 31 + 2 + 505 = 666.

It is not a de Polignac number, because 128312505 - 2¹² = 128308409 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128312507) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51589 + ... + 54018.

It is an arithmetic number, because the mean of its divisors is an integer number (9610328).

Almost surely, 2^128312505 is an apocalyptic number.

128312505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128312505 is a deficient number, since it is larger than the sum of its proper divisors (102335367).

128312505 is an equidigital number, since it uses as much as digits as its factorization.

128312505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105627 (or 105615 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 128312505 is about 11327.5109799108. The cubic root of 128312505 is about 504.3782237463.

The spelling of 128312505 in words is "one hundred twenty-eight million, three hundred twelve thousand, five hundred five".