18641281 has 4 divisors (see below), whose sum is σ = 19037952. Its totient is φ = 18244612.

The previous prime is 18641251. The next prime is 18641297. The reversal of 18641281 is 18214681.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18214681 = 521 ⋅34961.

It is a cyclic number.

It is not a de Polignac number, because 18641281 - 2⁷ = 18641153 is a prime.

It is a super-3 number, since 3×18641281³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18641251) 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, 198265 + ... + 198358.

It is an arithmetic number, because the mean of its divisors is an integer number (4759488).

Almost surely, 2^18641281 is an apocalyptic number.

It is an amenable number.

18641281 is a deficient number, since it is larger than the sum of its proper divisors (396671).

18641281 is an equidigital number, since it uses as much as digits as its factorization.

18641281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396670.

The product of its digits is 3072, while the sum is 31.

The square root of 18641281 is about 4317.5549793836. The cubic root of 18641281 is about 265.1501747593.

The spelling of 18641281 in words is "eighteen million, six hundred forty-one thousand, two hundred eighty-one".