90107821 has 2 divisors, whose sum is σ = 90107822. Its totient is φ = 90107820.

The previous prime is 90107819. The next prime is 90107851. The reversal of 90107821 is 12870109.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88454025 + 1653796 = 9405^2 + 1286^2 .

It is a cyclic number.

It is not a de Polignac number, because 90107821 - 2¹ = 90107819 is a prime.

Together with 90107819, 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 90107821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90107851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45053910 + 45053911.

It is an arithmetic number, because the mean of its divisors is an integer number (45053911).

Almost surely, 2^90107821 is an apocalyptic number.

It is an amenable number.

90107821 is a deficient number, since it is larger than the sum of its proper divisors (1).

90107821 is an equidigital number, since it uses as much as digits as its factorization.

90107821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 90107821 is about 9492.5139452097. The cubic root of 90107821 is about 448.3193623276.

The spelling of 90107821 in words is "ninety million, one hundred seven thousand, eight hundred twenty-one".