18501650581 has 2 divisors, whose sum is σ = 18501650582. Its totient is φ = 18501650580.

The previous prime is 18501650569. The next prime is 18501650597. The reversal of 18501650581 is 18505610581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14873997681 + 3627652900 = 121959^2 + 60230^2 .

It is a cyclic number.

It is not a de Polignac number, because 18501650581 - 2¹¹ = 18501648533 is a prime.

It is a super-2 number, since 2×18501650581² (a number of 21 digits) contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18501600581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9250825290 + 9250825291.

It is an arithmetic number, because the mean of its divisors is an integer number (9250825291).

Almost surely, 2^18501650581 is an apocalyptic number.

It is an amenable number.

18501650581 is a deficient number, since it is larger than the sum of its proper divisors (1).

18501650581 is an equidigital number, since it uses as much as digits as its factorization.

18501650581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48000, while the sum is 40.

The spelling of 18501650581 in words is "eighteen billion, five hundred one million, six hundred fifty thousand, five hundred eighty-one".