18416381 has 4 divisors (see below), whose sum is σ = 18469500. Its totient is φ = 18363264.

The previous prime is 18416371. The next prime is 18416383. The reversal of 18416381 is 18361481.

18416381 = 3034² + 3035².

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18361481 = 41 ⋅447841.

It can be written as a sum of positive squares in 2 ways, for example, as 9211225 + 9205156 = 3035^2 + 3034^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18416381 is a prime.

It is a super-2 number, since 2×18416381² = 678326178274322, 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 (18416383) 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, 26036 + ... + 26733.

It is an arithmetic number, because the mean of its divisors is an integer number (4617375).

Almost surely, 2^18416381 is an apocalyptic number.

18416381 is the 3035-th centered square number.

It is an amenable number.

18416381 is a deficient number, since it is larger than the sum of its proper divisors (53119).

18416381 is an equidigital number, since it uses as much as digits as its factorization.

18416381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53118.

The product of its digits is 4608, while the sum is 32.

The square root of 18416381 is about 4291.4311132768. The cubic root of 18416381 is about 264.0795453978.

The spelling of 18416381 in words is "eighteen million, four hundred sixteen thousand, three hundred eighty-one".