18550531 has 2 divisors, whose sum is σ = 18550532. Its totient is φ = 18550530.

The previous prime is 18550513. The next prime is 18550559. The reversal of 18550531 is 13505581.

Together with previous prime (18550513) it forms an Ormiston pair, because they use the same digits, order apart.

It is an a-pointer prime, because the next prime (18550559) can be obtained adding 18550531 to its sum of digits (28).

It is a weak prime.

It is an emirp because it is prime and its reverse (13505581) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18550531 - 2¹¹ = 18548483 is a prime.

It is a super-2 number, since 2×18550531² = 688244400763922, which contains 22 as substring.

It is equal to p_1184167 and since 18550531 and 1184167 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18550531.

It is not a weakly prime, because it can be changed into another prime (18550561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9275265 + 9275266.

It is an arithmetic number, because the mean of its divisors is an integer number (9275266).

Almost surely, 2^18550531 is an apocalyptic number.

18550531 is a deficient number, since it is larger than the sum of its proper divisors (1).

18550531 is an equidigital number, since it uses as much as digits as its factorization.

18550531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3000, while the sum is 28.

The square root of 18550531 is about 4307.0327372798. The cubic root of 18550531 is about 264.7192041739.

The spelling of 18550531 in words is "eighteen million, five hundred fifty thousand, five hundred thirty-one".