28288771821 has 12 divisors (see below), whose sum is σ = 41135799900. Its totient is φ = 18732608640.

The previous prime is 28288771811. The next prime is 28288771843. The reversal of 28288771821 is 12817788282.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 3435249321 + 24853522500 = 58611^2 + 157650^2 .

It is not a de Polignac number, because 28288771821 - 2²⁹ = 27751900909 is a prime.

It is a super-2 number, since 2×28288771821² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28288771811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10546300 + ... + 10548981.

It is an arithmetic number, because the mean of its divisors is an integer number (3427983325).

Almost surely, 2^28288771821 is an apocalyptic number.

It is an amenable number.

28288771821 is a deficient number, since it is larger than the sum of its proper divisors (12847028079).

28288771821 is a wasteful number, since it uses less digits than its factorization.

28288771821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21095436 (or 21095433 counting only the distinct ones).

The product of its digits is 1605632, while the sum is 54.

The spelling of 28288771821 in words is "twenty-eight billion, two hundred eighty-eight million, seven hundred seventy-one thousand, eight hundred twenty-one".