28781771069 has 4 divisors (see below), whose sum is σ = 30474816444. Its totient is φ = 27088725696.

The previous prime is 28781771023. The next prime is 28781771071. The reversal of 28781771069 is 96017718782.

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 20457580900 + 8324190169 = 143030^2 + 91237^2 .

It is a cyclic number.

It is not a de Polignac number, because 28781771069 - 2³² = 24486803773 is a prime.

It is a super-2 number, since 2×28781771069² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28781771009) 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, 846522662 + ... + 846522695.

It is an arithmetic number, because the mean of its divisors is an integer number (7618704111).

Almost surely, 2^28781771069 is an apocalyptic number.

It is an amenable number.

28781771069 is a deficient number, since it is larger than the sum of its proper divisors (1693045375).

28781771069 is a wasteful number, since it uses less digits than its factorization.

28781771069 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1693045374.

The product of its (nonzero) digits is 2370816, while the sum is 56.

The spelling of 28781771069 in words is "twenty-eight billion, seven hundred eighty-one million, seven hundred seventy-one thousand, sixty-nine".