28777791 has 16 divisors (see below), whose sum is σ = 44471808. Its totient is φ = 16212000.

The previous prime is 28777783. The next prime is 28777811. The reversal of 28777791 is 19777782.

It is not a de Polignac number, because 28777791 - 2³ = 28777783 is a prime.

It is a super-2 number, since 2×28777791² = 1656322509679362, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28777791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28777291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8160 + ... + 11141.

It is an arithmetic number, because the mean of its divisors is an integer number (2779488).

Almost surely, 2^28777791 is an apocalyptic number.

28777791 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

28777791 is a deficient number, since it is larger than the sum of its proper divisors (15694017).

28777791 is a wasteful number, since it uses less digits than its factorization.

28777791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19382.

The product of its digits is 345744, while the sum is 48.

The square root of 28777791 is about 5364.4935455269. The cubic root of 28777791 is about 306.4449611854. Note that the first 3 decimals are identical.

Subtracting from 28777791 its reverse (19777782), we obtain a palindrome (9000009).

The spelling of 28777791 in words is "twenty-eight million, seven hundred seventy-seven thousand, seven hundred ninety-one".