28219281 has 4 divisors (see below), whose sum is σ = 37625712. Its totient is φ = 18812852.

The previous prime is 28219277. The next prime is 28219297. The reversal of 28219281 is 18291282.

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 28219281 - 2² = 28219277 is a prime.

It is a super-2 number, since 2×28219281² = 1592655640313922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28219211) 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, 4703211 + ... + 4703216.

It is an arithmetic number, because the mean of its divisors is an integer number (9406428).

Almost surely, 2^28219281 is an apocalyptic number.

It is an amenable number.

28219281 is a deficient number, since it is larger than the sum of its proper divisors (9406431).

28219281 is an equidigital number, since it uses as much as digits as its factorization.

28219281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9406430.

The product of its digits is 4608, while the sum is 33.

The square root of 28219281 is about 5312.1823199134. The cubic root of 28219281 is about 304.4495347517.

The spelling of 28219281 in words is "twenty-eight million, two hundred nineteen thousand, two hundred eighty-one".