18137381 has 4 divisors (see below), whose sum is σ = 19092000. Its totient is φ = 17182764.

The previous prime is 18137377. The next prime is 18137389. The reversal of 18137381 is 18373181.

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: 18373181 = 467 ⋅39343.

It is not a de Polignac number, because 18137381 - 2² = 18137377 is a prime.

It is a super-2 number, since 2×18137381² = 657929179078322, 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 (18137389) 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, 477281 + ... + 477318.

It is an arithmetic number, because the mean of its divisors is an integer number (4773000).

Almost surely, 2^18137381 is an apocalyptic number.

It is an amenable number.

18137381 is a deficient number, since it is larger than the sum of its proper divisors (954619).

18137381 is an equidigital number, since it uses as much as digits as its factorization.

18137381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 954618.

The product of its digits is 4032, while the sum is 32.

The square root of 18137381 is about 4258.8004179581. The cubic root of 18137381 is about 262.7391912031.

The spelling of 18137381 in words is "eighteen million, one hundred thirty-seven thousand, three hundred eighty-one".