28623281 has 4 divisors (see below), whose sum is σ = 28686372. Its totient is φ = 28560192.

The previous prime is 28623277. The next prime is 28623307. The reversal of 28623281 is 18232682.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15366400 + 13256881 = 3920^2 + 3641^2 .

It is a cyclic number.

It is not a de Polignac number, because 28623281 - 2² = 28623277 is a prime.

It is a super-2 number, since 2×28623281² = 1638584430409922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28623211) 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, 30860 + ... + 31773.

It is an arithmetic number, because the mean of its divisors is an integer number (7171593).

Almost surely, 2^28623281 is an apocalyptic number.

It is an amenable number.

28623281 is a deficient number, since it is larger than the sum of its proper divisors (63091).

28623281 is an equidigital number, since it uses as much as digits as its factorization.

28623281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63090.

The product of its digits is 9216, while the sum is 32.

The square root of 28623281 is about 5350.0729901563. The cubic root of 28623281 is about 305.8955351328.

The spelling of 28623281 in words is "twenty-eight million, six hundred twenty-three thousand, two hundred eighty-one".