90018781 has 2 divisors, whose sum is σ = 90018782. Its totient is φ = 90018780.

The previous prime is 90018767. The next prime is 90018787. The reversal of 90018781 is 18781009.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66096900 + 23921881 = 8130^2 + 4891^2 .

It is a cyclic number.

It is not a de Polignac number, because 90018781 - 2⁷ = 90018653 is a prime.

It is a super-2 number, since 2×90018781² = 16206761865451922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90018787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45009390 + 45009391.

It is an arithmetic number, because the mean of its divisors is an integer number (45009391).

Almost surely, 2^90018781 is an apocalyptic number.

It is an amenable number.

90018781 is a deficient number, since it is larger than the sum of its proper divisors (1).

90018781 is an equidigital number, since it uses as much as digits as its factorization.

90018781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 34.

The square root of 90018781 is about 9487.8227744831. The cubic root of 90018781 is about 448.1716448071.

The spelling of 90018781 in words is "ninety million, eighteen thousand, seven hundred eighty-one".