28705921273 has 4 divisors (see below), whose sum is σ = 28707152548. Its totient is φ = 28704690000.

The previous prime is 28705921271. The next prime is 28705921303. The reversal of 28705921273 is 37212950782.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17091117289 + 11614803984 = 130733^2 + 107772^2 .

It is a cyclic number.

It is not a de Polignac number, because 28705921273 - 2¹ = 28705921271 is a prime.

It is a super-2 number, since 2×28705921273² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28705921271) 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, 579978 + ... + 627523.

It is an arithmetic number, because the mean of its divisors is an integer number (7176788137).

Almost surely, 2^28705921273 is an apocalyptic number.

It is an amenable number.

28705921273 is a deficient number, since it is larger than the sum of its proper divisors (1231275).

28705921273 is a wasteful number, since it uses less digits than its factorization.

28705921273 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1231274.

The product of its (nonzero) digits is 423360, while the sum is 46.

The spelling of 28705921273 in words is "twenty-eight billion, seven hundred five million, nine hundred twenty-one thousand, two hundred seventy-three".