18139081 has 3 divisors (see below), whose sum is σ = 18143341. Its totient is φ = 18134822.

The previous prime is 18139073. The next prime is 18139087. The reversal of 18139081 is 18093181.

The square root of 18139081 is 4259.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18093181 = 31 ⋅583651.

It is not a de Polignac number, because 18139081 - 2³ = 18139073 is a prime.

It is a super-2 number, since 2×18139081² = 658052519049122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18139087) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2130 + ... + 6388.

Almost surely, 2^18139081 is an apocalyptic number.

18139081 is the 4259-th square number.

18139081 is the 2130-th centered octagonal number.

It is an amenable number.

18139081 is a deficient number, since it is larger than the sum of its proper divisors (4260).

18139081 is an frugal number, since it uses more digits than its factorization.

18139081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8518 (or 4259 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 31.

The cubic root of 18139081 is about 262.7473997141.

The spelling of 18139081 in words is "eighteen million, one hundred thirty-nine thousand, eighty-one".