221020399 has 2 divisors, whose sum is σ = 221020400. Its totient is φ = 221020398.

The previous prime is 221020391. The next prime is 221020403. The reversal of 221020399 is 993020122.

221020399 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221020399 - 2³ = 221020391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221020391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510199 + 110510200.

It is an arithmetic number, because the mean of its divisors is an integer number (110510200).

Almost surely, 2^221020399 is an apocalyptic number.

221020399 is a deficient number, since it is larger than the sum of its proper divisors (1).

221020399 is an equidigital number, since it uses as much as digits as its factorization.

221020399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 221020399 is about 14866.7548241033. The cubic root of 221020399 is about 604.6129610204.

The spelling of 221020399 in words is "two hundred twenty-one million, twenty thousand, three hundred ninety-nine".