18142781 has 4 divisors (see below), whose sum is σ = 18728064. Its totient is φ = 17557500.

The previous prime is 18142769. The next prime is 18142793. The reversal of 18142781 is 18724181.

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 an interprime number because it is at equal distance from previous prime (18142769) and next prime (18142793).

It is a cyclic number.

It is not a de Polignac number, because 18142781 - 2⁶ = 18142717 is a prime.

It is a super-2 number, since 2×18142781² = 658321004827922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18142181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 292595 + ... + 292656.

It is an arithmetic number, because the mean of its divisors is an integer number (4682016).

Almost surely, 2^18142781 is an apocalyptic number.

It is an amenable number.

18142781 is a deficient number, since it is larger than the sum of its proper divisors (585283).

18142781 is an equidigital number, since it uses as much as digits as its factorization.

18142781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585282.

The product of its digits is 3584, while the sum is 32.

The square root of 18142781 is about 4259.4343521177. The cubic root of 18142781 is about 262.7652635240.

The spelling of 18142781 in words is "eighteen million, one hundred forty-two thousand, seven hundred eighty-one".