1621017221 has 2 divisors, whose sum is σ = 1621017222. Its totient is φ = 1621017220.

The previous prime is 1621017199. The next prime is 1621017227. The reversal of 1621017221 is 1227101261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1598880196 + 22137025 = 39986^2 + 4705^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621017221 - 2⁶ = 1621017157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621017227) 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, 810508610 + 810508611.

It is an arithmetic number, because the mean of its divisors is an integer number (810508611).

Almost surely, 2^1621017221 is an apocalyptic number.

It is an amenable number.

1621017221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621017221 is an equidigital number, since it uses as much as digits as its factorization.

1621017221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 1621017221 is about 40261.8581414221. The cubic root of 1621017221 is about 1174.7060610146.

Adding to 1621017221 its reverse (1227101261), we get a palindrome (2848118482).

The spelling of 1621017221 in words is "one billion, six hundred twenty-one million, seventeen thousand, two hundred twenty-one".