28147881 has 4 divisors (see below), whose sum is σ = 37530512. Its totient is φ = 18765252.

The previous prime is 28147859. The next prime is 28147913. The reversal of 28147881 is 18874182.

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 28147881 - 2⁵ = 28147849 is a prime.

It is a super-2 number, since 2×28147881² = 1584606409580322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28147831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4691311 + ... + 4691316.

It is an arithmetic number, because the mean of its divisors is an integer number (9382628).

Almost surely, 2^28147881 is an apocalyptic number.

It is an amenable number.

28147881 is a deficient number, since it is larger than the sum of its proper divisors (9382631).

28147881 is an equidigital number, since it uses as much as digits as its factorization.

28147881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9382630.

The product of its digits is 28672, while the sum is 39.

The square root of 28147881 is about 5305.4576616914. The cubic root of 28147881 is about 304.1925466772.

The spelling of 28147881 in words is "twenty-eight million, one hundred forty-seven thousand, eight hundred eighty-one".