128021519 has 4 divisors (see below), whose sum is σ = 133587696. Its totient is φ = 122455344.

The previous prime is 128021503. The next prime is 128021549. The reversal of 128021519 is 915120821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 915120821 = 6569 ⋅139309.

It is a cyclic number.

It is not a de Polignac number, because 128021519 - 2⁴ = 128021503 is a prime.

It is a super-2 number, since 2×128021519² = 32779018654134722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128021491 and 128021500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128021549) 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, 2783054 + ... + 2783099.

It is an arithmetic number, because the mean of its divisors is an integer number (33396924).

Almost surely, 2^128021519 is an apocalyptic number.

128021519 is a deficient number, since it is larger than the sum of its proper divisors (5566177).

128021519 is an equidigital number, since it uses as much as digits as its factorization.

128021519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5566176.

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 128021519 is about 11314.6594734442. The cubic root of 128021519 is about 503.9966602932.

The spelling of 128021519 in words is "one hundred twenty-eight million, twenty-one thousand, five hundred nineteen".