28878770821 has 4 divisors (see below), whose sum is σ = 29285514144. Its totient is φ = 28472027500.

The previous prime is 28878770777. The next prime is 28878770831. The reversal of 28878770821 is 12807787882.

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 28878770821 - 2⁷ = 28878770693 is a prime.

It is a super-3 number, since 3×28878770821³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28878770831) 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 3 ways as a sum of consecutive naturals, for example, 203371555 + ... + 203371696.

It is an arithmetic number, because the mean of its divisors is an integer number (7321378536).

Almost surely, 2^28878770821 is an apocalyptic number.

It is an amenable number.

28878770821 is a deficient number, since it is larger than the sum of its proper divisors (406743323).

28878770821 is an equidigital number, since it uses as much as digits as its factorization.

28878770821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406743322.

The product of its (nonzero) digits is 5619712, while the sum is 58.

The spelling of 28878770821 in words is "twenty-eight billion, eight hundred seventy-eight million, seven hundred seventy thousand, eight hundred twenty-one".