18342781 has 4 divisors (see below), whose sum is σ = 18459772. Its totient is φ = 18225792.

The previous prime is 18342769. The next prime is 18342803. The reversal of 18342781 is 18724381.

It is a happy number.

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 3062500 + 15280281 = 1750^2 + 3909^2 .

It is a cyclic number.

It is not a de Polignac number, because 18342781 - 2¹⁵ = 18310013 is a prime.

It is a super-2 number, since 2×18342781² = 672915229627922, 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 (18342481) 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, 58260 + ... + 58573.

It is an arithmetic number, because the mean of its divisors is an integer number (4614943).

Almost surely, 2^18342781 is an apocalyptic number.

It is an amenable number.

18342781 is a deficient number, since it is larger than the sum of its proper divisors (116991).

18342781 is a wasteful number, since it uses less digits than its factorization.

18342781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116990.

The product of its digits is 10752, while the sum is 34.

The square root of 18342781 is about 4282.8473005700. The cubic root of 18342781 is about 263.7272828453.

The spelling of 18342781 in words is "eighteen million, three hundred forty-two thousand, seven hundred eighty-one".