128220784731 has 20 divisors (see below), whose sum is σ = 206273514832. Its totient is φ = 78905097648.

The previous prime is 128220784729. The next prime is 128220784777. The reversal of 128220784731 is 137487022821.

128220784731 is a `hidden beast` number, since 12 + 82 + 20 + 78 + 473 + 1 = 666.

It is not a de Polignac number, because 128220784731 - 2¹ = 128220784729 is a prime.

It is a super-2 number, since 2×128220784731² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128220784231) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 60882511 + ... + 60884616.

Almost surely, 2^128220784731 is an apocalyptic number.

128220784731 is a deficient number, since it is larger than the sum of its proper divisors (78052730101).

128220784731 is a wasteful number, since it uses less digits than its factorization.

128220784731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121767152 (or 121767143 counting only the distinct ones).

The product of its (nonzero) digits is 301056, while the sum is 45.

The spelling of 128220784731 in words is "one hundred twenty-eight billion, two hundred twenty million, seven hundred eighty-four thousand, seven hundred thirty-one".