28921081 has 4 divisors (see below), whose sum is σ = 33052672. Its totient is φ = 24789492.

The previous prime is 28921073. The next prime is 28921099. The reversal of 28921081 is 18012982.

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 not a de Polignac number, because 28921081 - 2³ = 28921073 is a prime.

It is a super-2 number, since 2×28921081² = 1672857852417122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28921681) 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, 2065785 + ... + 2065798.

It is an arithmetic number, because the mean of its divisors is an integer number (8263168).

Almost surely, 2^28921081 is an apocalyptic number.

It is an amenable number.

28921081 is a deficient number, since it is larger than the sum of its proper divisors (4131591).

28921081 is an equidigital number, since it uses as much as digits as its factorization.

28921081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4131590.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 28921081 is about 5377.8323700168. The cubic root of 28921081 is about 306.9527349277.

The spelling of 28921081 in words is "twenty-eight million, nine hundred twenty-one thousand, eighty-one".