28681881 has 4 divisors (see below), whose sum is σ = 38242512. Its totient is φ = 19121252.

The previous prime is 28681871. The next prime is 28681921. The reversal of 28681881 is 18818682.

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 28681881 - 2⁷ = 28681753 is a prime.

It is a super-2 number, since 2×28681881² = 1645300595396322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28681801) 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, 4780311 + ... + 4780316.

It is an arithmetic number, because the mean of its divisors is an integer number (9560628).

Almost surely, 2^28681881 is an apocalyptic number.

It is an amenable number.

28681881 is a deficient number, since it is larger than the sum of its proper divisors (9560631).

28681881 is an equidigital number, since it uses as much as digits as its factorization.

28681881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9560630.

The product of its digits is 49152, while the sum is 42.

The square root of 28681881 is about 5355.5467507996. The cubic root of 28681881 is about 306.1041445675.

The spelling of 28681881 in words is "twenty-eight million, six hundred eighty-one thousand, eight hundred eighty-one".