128240909 has 2 divisors, whose sum is σ = 128240910. Its totient is φ = 128240908.

The previous prime is 128240869. The next prime is 128240923. The reversal of 128240909 is 909042821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 116165284 + 12075625 = 10778^2 + 3475^2 .

It is a cyclic number.

It is not a de Polignac number, because 128240909 - 2¹⁶ = 128175373 is a prime.

It is a super-2 number, since 2×128240909² = 32891461482292562, which contains 22 as substring.

It is equal to p_7283951 and since 128240909 and 7283951 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128210909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64120454 + 64120455.

It is an arithmetic number, because the mean of its divisors is an integer number (64120455).

Almost surely, 2^128240909 is an apocalyptic number.

It is an amenable number.

128240909 is a deficient number, since it is larger than the sum of its proper divisors (1).

128240909 is an equidigital number, since it uses as much as digits as its factorization.

128240909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 128240909 is about 11324.3502683377. The cubic root of 128240909 is about 504.2843950586.

The spelling of 128240909 in words is "one hundred twenty-eight million, two hundred forty thousand, nine hundred nine".