128621791 has 2 divisors, whose sum is σ = 128621792. Its totient is φ = 128621790.

The previous prime is 128621777. The next prime is 128621809. The reversal of 128621791 is 197126821.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 128621791 - 2¹³ = 128613599 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128621791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128621761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64310895 + 64310896.

It is an arithmetic number, because the mean of its divisors is an integer number (64310896).

Almost surely, 2^128621791 is an apocalyptic number.

128621791 is a deficient number, since it is larger than the sum of its proper divisors (1).

128621791 is an equidigital number, since it uses as much as digits as its factorization.

128621791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 37.

The square root of 128621791 is about 11341.1547472028. The cubic root of 128621791 is about 504.7831516780.

The spelling of 128621791 in words is "one hundred twenty-eight million, six hundred twenty-one thousand, seven hundred ninety-one".