128321551 has 2 divisors, whose sum is σ = 128321552. Its totient is φ = 128321550.

The previous prime is 128321509. The next prime is 128321597. The reversal of 128321551 is 155123821.

It is a weak prime.

It is an emirp because it is prime and its reverse (155123821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128321551 - 2²⁵ = 94767119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123321551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64160775 + 64160776.

It is an arithmetic number, because the mean of its divisors is an integer number (64160776).

Almost surely, 2^128321551 is an apocalyptic number.

128321551 is a deficient number, since it is larger than the sum of its proper divisors (1).

128321551 is an equidigital number, since it uses as much as digits as its factorization.

128321551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2400, while the sum is 28.

The square root of 128321551 is about 11327.9102662406. The cubic root of 128321551 is about 504.3900763147.

The spelling of 128321551 in words is "one hundred twenty-eight million, three hundred twenty-one thousand, five hundred fifty-one".