28685921909 has 16 divisors (see below), whose sum is σ = 30377973120. Its totient is φ = 27041273280.

The previous prime is 28685921903. The next prime is 28685921923. The reversal of 28685921909 is 90912958682.

It is a cyclic number.

It is not a de Polignac number, because 28685921909 - 2¹⁶ = 28685856373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28685921903) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5273339 + ... + 5278775.

It is an arithmetic number, because the mean of its divisors is an integer number (1898623320).

Almost surely, 2^28685921909 is an apocalyptic number.

28685921909 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

28685921909 is a deficient number, since it is larger than the sum of its proper divisors (1692051211).

28685921909 is a wasteful number, since it uses less digits than its factorization.

28685921909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9740.

The product of its (nonzero) digits is 5598720, while the sum is 59.

The spelling of 28685921909 in words is "twenty-eight billion, six hundred eighty-five million, nine hundred twenty-one thousand, nine hundred nine".