128720551 has 2 divisors, whose sum is σ = 128720552. Its totient is φ = 128720550.

The previous prime is 128720539. The next prime is 128720609. The reversal of 128720551 is 155027821.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 128720551 - 2⁵ = 128720519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128720051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64360275 + 64360276.

It is an arithmetic number, because the mean of its divisors is an integer number (64360276).

Almost surely, 2^128720551 is an apocalyptic number.

128720551 is a deficient number, since it is larger than the sum of its proper divisors (1).

128720551 is an equidigital number, since it uses as much as digits as its factorization.

128720551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600, while the sum is 31.

The square root of 128720551 is about 11345.5079657105. The cubic root of 128720551 is about 504.9123149395.

The spelling of 128720551 in words is "one hundred twenty-eight million, seven hundred twenty thousand, five hundred fifty-one".