18157381 has 6 divisors (see below), whose sum is σ = 19958246. Its totient is φ = 16506600.

The previous prime is 18157379. The next prime is 18157421. The reversal of 18157381 is 18375181.

It can be written as a sum of positive squares in only one way, i.e., 17564481 + 592900 = 4191^2 + 770^2 .

It is not a de Polignac number, because 18157381 - 2¹ = 18157379 is a prime.

It is a super-2 number, since 2×18157381² = 659380969558322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18157361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 74910 + ... + 75151.

Almost surely, 2^18157381 is an apocalyptic number.

18157381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18157381 is a deficient number, since it is larger than the sum of its proper divisors (1800865).

18157381 is a wasteful number, since it uses less digits than its factorization.

18157381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150083 (or 150072 counting only the distinct ones).

The product of its digits is 6720, while the sum is 34.

The square root of 18157381 is about 4261.1478500517. The cubic root of 18157381 is about 262.8357294617.

The spelling of 18157381 in words is "eighteen million, one hundred fifty-seven thousand, three hundred eighty-one".