3621660821221 has 2 divisors, whose sum is σ = 3621660821222. Its totient is φ = 3621660821220.

The previous prime is 3621660821203. The next prime is 3621660821231. The reversal of 3621660821221 is 1221280661263.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3323529533025 + 298131288196 = 1823055^2 + 546014^2 .

It is a cyclic number.

It is not a de Polignac number, because 3621660821221 - 2²⁷ = 3621526603493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3621660821231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1810830410610 + 1810830410611.

It is an arithmetic number, because the mean of its divisors is an integer number (1810830410611).

Almost surely, 2^{3621660821221} is an apocalyptic number.

It is an amenable number.

3621660821221 is a deficient number, since it is larger than the sum of its proper divisors (1).

3621660821221 is an equidigital number, since it uses as much as digits as its factorization.

3621660821221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 82944, while the sum is 40.

The spelling of 3621660821221 in words is "three trillion, six hundred twenty-one billion, six hundred sixty million, eight hundred twenty-one thousand, two hundred twenty-one".