1820100221 has 2 divisors, whose sum is σ = 1820100222. Its totient is φ = 1820100220.

The previous prime is 1820100181. The next prime is 1820100229. The reversal of 1820100221 is 1220010281.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 928420900 + 891679321 = 30470^2 + 29861^2 .

It is a cyclic number.

It is not a de Polignac number, because 1820100221 - 2¹⁸ = 1819838077 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1820100221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1820100229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910050110 + 910050111.

It is an arithmetic number, because the mean of its divisors is an integer number (910050111).

Almost surely, 2^1820100221 is an apocalyptic number.

It is an amenable number.

1820100221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820100221 is an equidigital number, since it uses as much as digits as its factorization.

1820100221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 1820100221 is about 42662.6326074704. The cubic root of 1820100221 is about 1220.9515600937.

The spelling of 1820100221 in words is "one billion, eight hundred twenty million, one hundred thousand, two hundred twenty-one".