28191481 has 4 divisors (see below), whose sum is σ = 28265472. Its totient is φ = 28117492.

The previous prime is 28191467. The next prime is 28191517. The reversal of 28191481 is 18419182.

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 28191481 - 2¹⁹ = 27667193 is a prime.

It is a super-2 number, since 2×28191481² = 1589519201946722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28191281) 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, 36421 + ... + 37186.

It is an arithmetic number, because the mean of its divisors is an integer number (7066368).

Almost surely, 2^28191481 is an apocalyptic number.

It is an amenable number.

28191481 is a deficient number, since it is larger than the sum of its proper divisors (73991).

28191481 is an equidigital number, since it uses as much as digits as its factorization.

28191481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73990.

The product of its digits is 4608, while the sum is 34.

The square root of 28191481 is about 5309.5650480995. The cubic root of 28191481 is about 304.3495265587.

The spelling of 28191481 in words is "twenty-eight million, one hundred ninety-one thousand, four hundred eighty-one".