1811090221 has 2 divisors, whose sum is σ = 1811090222. Its totient is φ = 1811090220.

The previous prime is 1811090207. The next prime is 1811090227. The reversal of 1811090221 is 1220901181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1435273225 + 375816996 = 37885^2 + 19386^2 .

It is a cyclic number.

It is not a de Polignac number, because 1811090221 - 2⁷ = 1811090093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1811090227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905545110 + 905545111.

It is an arithmetic number, because the mean of its divisors is an integer number (905545111).

Almost surely, 2^1811090221 is an apocalyptic number.

It is an amenable number.

1811090221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811090221 is an equidigital number, since it uses as much as digits as its factorization.

1811090221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 25.

The square root of 1811090221 is about 42556.9056793372. The cubic root of 1811090221 is about 1218.9335437582.

The spelling of 1811090221 in words is "one billion, eight hundred eleven million, ninety thousand, two hundred twenty-one".