28821909 has 16 divisors (see below), whose sum is σ = 39813120. Its totient is φ = 18527280.

The previous prime is 28821887. The next prime is 28821931. The reversal of 28821909 is 90912882.

It is an interprime number because it is at equal distance from previous prime (28821887) and next prime (28821931).

It is not a de Polignac number, because 28821909 - 2⁷ = 28821781 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28821959) 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, 44224 + ... + 44870.

It is an arithmetic number, because the mean of its divisors is an integer number (2488320).

Almost surely, 2^28821909 is an apocalyptic number.

It is an amenable number.

28821909 is a deficient number, since it is larger than the sum of its proper divisors (10991211).

28821909 is a wasteful number, since it uses less digits than its factorization.

28821909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1160.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 28821909 is about 5368.6040084923. The cubic root of 28821909 is about 306.6014804474.

The spelling of 28821909 in words is "twenty-eight million, eight hundred twenty-one thousand, nine hundred nine".