18403381 has 12 divisors (see below), whose sum is σ = 20261920. Its totient is φ = 16667640.

The previous prime is 18403379. The next prime is 18403387. The reversal of 18403381 is 18330481.

It is not a de Polignac number, because 18403381 - 2¹ = 18403379 is a prime.

It is a super-2 number, since 2×18403381² = 677368864462322, which contains 22 as substring.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18403387) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9136 + ... + 10966.

Almost surely, 2^18403381 is an apocalyptic number.

It is an amenable number.

18403381 is a deficient number, since it is larger than the sum of its proper divisors (1858539).

18403381 is a wasteful number, since it uses less digits than its factorization.

18403381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1896 (or 1873 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 18403381 is about 4289.9161996477. The cubic root of 18403381 is about 264.0173934439.

Subtracting from 18403381 its reverse (18330481), we obtain a square (72900 = 270²).

The spelling of 18403381 in words is "eighteen million, four hundred three thousand, three hundred eighty-one".