18012539 has 4 divisors (see below), whose sum is σ = 18172056. Its totient is φ = 17853024.

The previous prime is 18012499. The next prime is 18012541. The reversal of 18012539 is 93521081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93521081 = 229 ⋅408389.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18012539 is a prime.

It is a super-2 number, since 2×18012539² = 648903122453042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18012559) 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, 79589 + ... + 79814.

It is an arithmetic number, because the mean of its divisors is an integer number (4543014).

Almost surely, 2^18012539 is an apocalyptic number.

18012539 is a deficient number, since it is larger than the sum of its proper divisors (159517).

18012539 is a wasteful number, since it uses less digits than its factorization.

18012539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159516.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 18012539 is about 4244.1181651787. The cubic root of 18012539 is about 262.1349798815.

The spelling of 18012539 in words is "eighteen million, twelve thousand, five hundred thirty-nine".