128999501 has 6 divisors (see below), whose sum is σ = 132581610. Its totient is φ = 125511696.

The previous prime is 128999491. The next prime is 128999503. The reversal of 128999501 is 105999821.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 98208100 + 30791401 = 9910^2 + 5549^2 .

It is not a de Polignac number, because 128999501 - 2¹⁰ = 128998477 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128999503) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 45746 + ... + 48483.

It is an arithmetic number, because the mean of its divisors is an integer number (22096935).

Almost surely, 2^128999501 is an apocalyptic number.

It is an amenable number.

128999501 is a deficient number, since it is larger than the sum of its proper divisors (3582109).

128999501 is an frugal number, since it uses more digits than its factorization.

128999501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94303 (or 94266 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 44.

The square root of 128999501 is about 11357.7947243292. The cubic root of 128999501 is about 505.2767832124.

The spelling of 128999501 in words is "one hundred twenty-eight million, nine hundred ninety-nine thousand, five hundred one".