18001281 has 4 divisors (see below), whose sum is σ = 24001712. Its totient is φ = 12000852.

The previous prime is 18001273. The next prime is 18001307. The reversal of 18001281 is 18210081.

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: 18210081 = 3 ⋅6070027.

It is not a de Polignac number, because 18001281 - 2³ = 18001273 is a prime.

It is a super-2 number, since 2×18001281² = 648092235281922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18001201) 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, 3000211 + ... + 3000216.

It is an arithmetic number, because the mean of its divisors is an integer number (6000428).

Almost surely, 2^18001281 is an apocalyptic number.

It is an amenable number.

18001281 is a deficient number, since it is larger than the sum of its proper divisors (6000431).

18001281 is an equidigital number, since it uses as much as digits as its factorization.

18001281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6000430.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 18001281 is about 4242.7916517312. The cubic root of 18001281 is about 262.0803562544.

It can be divided in two parts, 1800 and 1281, that added together give a triangular number (3081 = T₇₈).

The spelling of 18001281 in words is "eighteen million, one thousand, two hundred eighty-one".