90431521 has 2 divisors, whose sum is σ = 90431522. Its totient is φ = 90431520.

The previous prime is 90431503. The next prime is 90431531. The reversal of 90431521 is 12513409.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71639296 + 18792225 = 8464^2 + 4335^2 .

It is an emirp because it is prime and its reverse (12513409) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 90431521 - 2¹³ = 90423329 is a prime.

It is not a weakly prime, because it can be changed into another prime (90431531) 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, 45215760 + 45215761.

It is an arithmetic number, because the mean of its divisors is an integer number (45215761).

Almost surely, 2^90431521 is an apocalyptic number.

It is an amenable number.

90431521 is a deficient number, since it is larger than the sum of its proper divisors (1).

90431521 is an equidigital number, since it uses as much as digits as its factorization.

90431521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 90431521 is about 9509.5489377783. The cubic root of 90431521 is about 448.8555627233.

The spelling of 90431521 in words is "ninety million, four hundred thirty-one thousand, five hundred twenty-one".