20781778428 has 72 divisors (see below), whose sum is σ = 55324680320. Its totient is φ = 6559328160.

The previous prime is 20781778397. The next prime is 20781778463. The reversal of 20781778428 is 82487718702.

20781778428 is a `hidden beast` number, since 207 + 8 + 1 + 7 + 7 + 8 + 428 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1574151 + ... + 1587297.

Almost surely, 2^20781778428 is an apocalyptic number.

It is an amenable number.

20781778428 is an abundant number, since it is smaller than the sum of its proper divisors (34542901892).

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

20781778428 is a wasteful number, since it uses less digits than its factorization.

20781778428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15487 (or 15482 counting only the distinct ones).

The product of its (nonzero) digits is 2809856, while the sum is 54.

The spelling of 20781778428 in words is "twenty billion, seven hundred eighty-one million, seven hundred seventy-eight thousand, four hundred twenty-eight".