18051391 has 4 divisors (see below), whose sum is σ = 18099400. Its totient is φ = 18003384.

The previous prime is 18051379. The next prime is 18051403. The reversal of 18051391 is 19315081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19315081 = 661 ⋅29221.

It is an interprime number because it is at equal distance from previous prime (18051379) and next prime (18051403).

It is a 3-Lehmer number, since φ(18051391) divides (18051391-1)³.

It is a cyclic number.

It is not a de Polignac number, because 18051391 - 2¹⁷ = 17920319 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18051191) 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, 23436 + ... + 24193.

It is an arithmetic number, because the mean of its divisors is an integer number (4524850).

Almost surely, 2^18051391 is an apocalyptic number.

18051391 is a deficient number, since it is larger than the sum of its proper divisors (48009).

18051391 is an equidigital number, since it uses as much as digits as its factorization.

18051391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48008.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 18051391 is about 4248.6928578093. The cubic root of 18051391 is about 262.3233145108.

The spelling of 18051391 in words is "eighteen million, fifty-one thousand, three hundred ninety-one".