221079821 has 2 divisors, whose sum is σ = 221079822. Its totient is φ = 221079820.

The previous prime is 221079797. The next prime is 221079863. The reversal of 221079821 is 128970122.

It is a happy number.

221079821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 186622921 + 34456900 = 13661^2 + 5870^2 .

It is a cyclic number.

It is not a de Polignac number, because 221079821 - 2⁶ = 221079757 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221072821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110539910 + 110539911.

It is an arithmetic number, because the mean of its divisors is an integer number (110539911).

Almost surely, 2^221079821 is an apocalyptic number.

It is an amenable number.

221079821 is a deficient number, since it is larger than the sum of its proper divisors (1).

221079821 is an equidigital number, since it uses as much as digits as its factorization.

221079821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 221079821 is about 14868.7531757037. The cubic root of 221079821 is about 604.6671401705.

The spelling of 221079821 in words is "two hundred twenty-one million, seventy-nine thousand, eight hundred twenty-one".