128320831 has 2 divisors, whose sum is σ = 128320832. Its totient is φ = 128320830.

The previous prime is 128320817. The next prime is 128320861. The reversal of 128320831 is 138023821.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128320831 is a prime.

It is a super-2 number, since 2×128320831² = 32932471337061122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 128320831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128320861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64160415 + 64160416.

It is an arithmetic number, because the mean of its divisors is an integer number (64160416).

Almost surely, 2^128320831 is an apocalyptic number.

128320831 is a deficient number, since it is larger than the sum of its proper divisors (1).

128320831 is an equidigital number, since it uses as much as digits as its factorization.

128320831 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 128320831 is about 11327.8784862833. The cubic root of 128320831 is about 504.3891329513.

The spelling of 128320831 in words is "one hundred twenty-eight million, three hundred twenty thousand, eight hundred thirty-one".