221036021 has 2 divisors, whose sum is σ = 221036022. Its totient is φ = 221036020.

The previous prime is 221036017. The next prime is 221036051. The reversal of 221036021 is 120630122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216413521 + 4622500 = 14711^2 + 2150^2 .

It is a cyclic number.

It is not a de Polignac number, because 221036021 - 2² = 221036017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221036051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110518010 + 110518011.

It is an arithmetic number, because the mean of its divisors is an integer number (110518011).

Almost surely, 2^221036021 is an apocalyptic number.

It is an amenable number.

221036021 is a deficient number, since it is larger than the sum of its proper divisors (1).

221036021 is an equidigital number, since it uses as much as digits as its factorization.

221036021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 221036021 is about 14867.2802152916. The cubic root of 221036021 is about 604.6272056198.

Adding to 221036021 its reverse (120630122), we get a palindrome (341666143).

The spelling of 221036021 in words is "two hundred twenty-one million, thirty-six thousand, twenty-one".