128521655 has 4 divisors (see below), whose sum is σ = 154225992. Its totient is φ = 102817320.

The previous prime is 128521651. The next prime is 128521663. The reversal of 128521655 is 556125821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 556125821 = 1669 ⋅333209.

It is not a de Polignac number, because 128521655 - 2² = 128521651 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128521651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12852161 + ... + 12852170.

It is an arithmetic number, because the mean of its divisors is an integer number (38556498).

Almost surely, 2^128521655 is an apocalyptic number.

128521655 is a deficient number, since it is larger than the sum of its proper divisors (25704337).

128521655 is an equidigital number, since it uses as much as digits as its factorization.

128521655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25704336.

The product of its digits is 24000, while the sum is 35.

The square root of 128521655 is about 11336.7391696202. The cubic root of 128521655 is about 504.6521212919.

The spelling of 128521655 in words is "one hundred twenty-eight million, five hundred twenty-one thousand, six hundred fifty-five".