28776881 has 4 divisors (see below), whose sum is σ = 32887872. Its totient is φ = 24665892.

The previous prime is 28776863. The next prime is 28776911. The reversal of 28776881 is 18867782.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28776881 - 2¹⁸ = 28514737 is a prime.

It is a super-2 number, since 2×28776881² = 1656217760176322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28776821) 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, 2055485 + ... + 2055498.

It is an arithmetic number, because the mean of its divisors is an integer number (8221968).

Almost surely, 2^28776881 is an apocalyptic number.

It is an amenable number.

28776881 is a deficient number, since it is larger than the sum of its proper divisors (4110991).

28776881 is an equidigital number, since it uses as much as digits as its factorization.

28776881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4110990.

The product of its digits is 301056, while the sum is 47.

The square root of 28776881 is about 5364.4087279028. The cubic root of 28776881 is about 306.4417310573.

Subtracting from 28776881 its reverse (18867782), we obtain a palindrome (9909099).

The spelling of 28776881 in words is "twenty-eight million, seven hundred seventy-six thousand, eight hundred eighty-one".