128235905261 has 2 divisors, whose sum is σ = 128235905262. Its totient is φ = 128235905260.

The previous prime is 128235905257. The next prime is 128235905269. The reversal of 128235905261 is 162509532821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 95932672900 + 32303232361 = 309730^2 + 179731^2 .

It is a cyclic number.

It is not a de Polignac number, because 128235905261 - 2² = 128235905257 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128235905269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64117952630 + 64117952631.

It is an arithmetic number, because the mean of its divisors is an integer number (64117952631).

Almost surely, 2^128235905261 is an apocalyptic number.

It is an amenable number.

128235905261 is a deficient number, since it is larger than the sum of its proper divisors (1).

128235905261 is an equidigital number, since it uses as much as digits as its factorization.

128235905261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 259200, while the sum is 44.

The spelling of 128235905261 in words is "one hundred twenty-eight billion, two hundred thirty-five million, nine hundred five thousand, two hundred sixty-one".