128791669 has 2 divisors, whose sum is σ = 128791670. Its totient is φ = 128791668.

The previous prime is 128791667. The next prime is 128791673. The reversal of 128791669 is 966197821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 101103025 + 27688644 = 10055^2 + 5262^2 .

It is a cyclic number.

It is not a de Polignac number, because 128791669 - 2¹ = 128791667 is a prime.

It is a super-2 number, since 2×128791669² = 33174588007611122, which contains 22 as substring.

Together with 128791667, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128791667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64395834 + 64395835.

It is an arithmetic number, because the mean of its divisors is an integer number (64395835).

Almost surely, 2^128791669 is an apocalyptic number.

It is an amenable number.

128791669 is a deficient number, since it is larger than the sum of its proper divisors (1).

128791669 is an equidigital number, since it uses as much as digits as its factorization.

128791669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 49.

The square root of 128791669 is about 11348.6417248938. The cubic root of 128791669 is about 505.0052857010.

The spelling of 128791669 in words is "one hundred twenty-eight million, seven hundred ninety-one thousand, six hundred sixty-nine".