18031481 has 4 divisors (see below), whose sum is σ = 19418532. Its totient is φ = 16644432.

The previous prime is 18031463. The next prime is 18031483. The reversal of 18031481 is 18413081.

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 883600 + 17147881 = 940^2 + 4141^2 .

It is a cyclic number.

It is not a de Polignac number, because 18031481 - 2²² = 13837177 is a prime.

It is a super-2 number, since 2×18031481² = 650268614106722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18031481.

It is not an unprimeable number, because it can be changed into a prime (18031483) 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, 693506 + ... + 693531.

It is an arithmetic number, because the mean of its divisors is an integer number (4854633).

Almost surely, 2^18031481 is an apocalyptic number.

It is an amenable number.

18031481 is a deficient number, since it is larger than the sum of its proper divisors (1387051).

18031481 is a wasteful number, since it uses less digits than its factorization.

18031481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1387050.

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 18031481 is about 4246.3491377888. The cubic root of 18031481 is about 262.2268348069.

The spelling of 18031481 in words is "eighteen million, thirty-one thousand, four hundred eighty-one".