18531643 has 4 divisors (see below), whose sum is σ = 19957168. Its totient is φ = 17106120.

The previous prime is 18531641. The next prime is 18531673. The reversal of 18531643 is 34613581.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18531643 - 2¹ = 18531641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18531641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 712743 + ... + 712768.

It is an arithmetic number, because the mean of its divisors is an integer number (4989292).

Almost surely, 2^18531643 is an apocalyptic number.

18531643 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

18531643 is a deficient number, since it is larger than the sum of its proper divisors (1425525).

18531643 is a wasteful number, since it uses less digits than its factorization.

18531643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1425524.

The product of its digits is 8640, while the sum is 31.

The square root of 18531643 is about 4304.8394859739. The cubic root of 18531643 is about 264.6293286823.

The spelling of 18531643 in words is "eighteen million, five hundred thirty-one thousand, six hundred forty-three".