21185782128 has 60 divisors (see below), whose sum is σ = 67760877808. Its totient is φ = 6053080320.

The previous prime is 21185782099. The next prime is 21185782129. The reversal of 21185782128 is 82128758112.

21185782128 is a `hidden beast` number, since 21 + 18 + 578 + 21 + 28 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185782129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10507813 + ... + 10509828.

Almost surely, 2^21185782128 is an apocalyptic number.

21185782128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21185782128 is an abundant number, since it is smaller than the sum of its proper divisors (46575095680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21185782128 is a wasteful number, since it uses less digits than its factorization.

21185782128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21017662 (or 21017653 counting only the distinct ones).

The product of its digits is 143360, while the sum is 45.

The spelling of 21185782128 in words is "twenty-one billion, one hundred eighty-five million, seven hundred eighty-two thousand, one hundred twenty-eight".