90306721 has 2 divisors, whose sum is σ = 90306722. Its totient is φ = 90306720.

The previous prime is 90306719. The next prime is 90306773. The reversal of 90306721 is 12760309.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71166096 + 19140625 = 8436^2 + 4375^2 .

It is an emirp because it is prime and its reverse (12760309) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 90306721 - 2¹ = 90306719 is a prime.

Together with 90306719, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 90306721.

It is not a weakly prime, because it can be changed into another prime (90303721) 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, 45153360 + 45153361.

It is an arithmetic number, because the mean of its divisors is an integer number (45153361).

Almost surely, 2^90306721 is an apocalyptic number.

It is an amenable number.

90306721 is a deficient number, since it is larger than the sum of its proper divisors (1).

90306721 is an equidigital number, since it uses as much as digits as its factorization.

90306721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 90306721 is about 9502.9848468784. The cubic root of 90306721 is about 448.6489866599.

It can be divided in two parts, 9030 and 6721, that added together give a palindrome (15751).

The spelling of 90306721 in words is "ninety million, three hundred six thousand, seven hundred twenty-one".