90208021 has 2 divisors, whose sum is σ = 90208022. Its totient is φ = 90208020.

The previous prime is 90208003. The next prime is 90208031. The reversal of 90208021 is 12080209.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70056900 + 20151121 = 8370^2 + 4489^2 .

It is a cyclic number.

It is not a de Polignac number, because 90208021 - 2⁵ = 90207989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 90207983 and 90208001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90208031) 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, 45104010 + 45104011.

It is an arithmetic number, because the mean of its divisors is an integer number (45104011).

Almost surely, 2^90208021 is an apocalyptic number.

It is an amenable number.

90208021 is a deficient number, since it is larger than the sum of its proper divisors (1).

90208021 is an equidigital number, since it uses as much as digits as its factorization.

90208021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 90208021 is about 9497.7903219644. The cubic root of 90208021 is about 448.4854779837.

The spelling of 90208021 in words is "ninety million, two hundred eight thousand, twenty-one".