28321664781 has 16 divisors (see below), whose sum is σ = 38703553856. Its totient is φ = 18411878016.

The previous prime is 28321664779. The next prime is 28321664843. The reversal of 28321664781 is 18746612382.

It is not a de Polignac number, because 28321664781 - 2¹ = 28321664779 is a prime.

It is a super-2 number, since 2×28321664781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28321664781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28321664711) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100000 + ... + 258153.

It is an arithmetic number, because the mean of its divisors is an integer number (2418972116).

Almost surely, 2^28321664781 is an apocalyptic number.

It is an amenable number.

28321664781 is a deficient number, since it is larger than the sum of its proper divisors (10381889075).

28321664781 is a wasteful number, since it uses less digits than its factorization.

28321664781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358812.

The product of its digits is 774144, while the sum is 48.

The spelling of 28321664781 in words is "twenty-eight billion, three hundred twenty-one million, six hundred sixty-four thousand, seven hundred eighty-one".