18812281 has 4 divisors (see below), whose sum is σ = 18822564. Its totient is φ = 18802000.

The previous prime is 18812273. The next prime is 18812291. The reversal of 18812281 is 18221881.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18221881 = 331 ⋅55051.

It can be written as a sum of positive squares in 2 ways, for example, as 4372281 + 14440000 = 2091^2 + 3800^2 .

It is a cyclic number.

It is not a de Polignac number, because 18812281 - 2³ = 18812273 is a prime.

It is a super-2 number, since 2×18812281² = 707803832845922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18812221) 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, 1570 + ... + 6331.

It is an arithmetic number, because the mean of its divisors is an integer number (4705641).

Almost surely, 2^18812281 is an apocalyptic number.

It is an amenable number.

18812281 is a deficient number, since it is larger than the sum of its proper divisors (10283).

18812281 is an equidigital number, since it uses as much as digits as its factorization.

18812281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10282.

The product of its digits is 2048, while the sum is 31.

The square root of 18812281 is about 4337.3126472506. The cubic root of 18812281 is about 265.9584658236.

The spelling of 18812281 in words is "eighteen million, eight hundred twelve thousand, two hundred eighty-one".