18499561 has 2 divisors, whose sum is σ = 18499562. Its totient is φ = 18499560.

The previous prime is 18499541. The next prime is 18499601. The reversal of 18499561 is 16599481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16000000 + 2499561 = 4000^2 + 1581^2 .

It is a cyclic number.

It is not a de Polignac number, because 18499561 - 2⁷ = 18499433 is a prime.

It is not a weakly prime, because it can be changed into another prime (18499541) 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 as a sum of consecutive naturals, namely, 9249780 + 9249781.

It is an arithmetic number, because the mean of its divisors is an integer number (9249781).

Almost surely, 2^18499561 is an apocalyptic number.

It is an amenable number.

18499561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18499561 is an equidigital number, since it uses as much as digits as its factorization.

18499561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 43.

The square root of 18499561 is about 4301.1116005052. Note that the first 3 decimals coincide. The cubic root of 18499561 is about 264.4765316161.

The spelling of 18499561 in words is "eighteen million, four hundred ninety-nine thousand, five hundred sixty-one".