221111021 has 2 divisors, whose sum is σ = 221111022. Its totient is φ = 221111020.

The previous prime is 221110997. The next prime is 221111039. The reversal of 221111021 is 120111122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162282121 + 58828900 = 12739^2 + 7670^2 .

It is a cyclic number.

It is not a de Polignac number, because 221111021 - 2¹⁸ = 220848877 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 221110993 and 221111011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221111041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110555510 + 110555511.

It is an arithmetic number, because the mean of its divisors is an integer number (110555511).

Almost surely, 2^221111021 is an apocalyptic number.

It is an amenable number.

221111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

221111021 is an equidigital number, since it uses as much as digits as its factorization.

221111021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 11.

The square root of 221111021 is about 14869.8023187936. The cubic root of 221111021 is about 604.6955834831.

Adding to 221111021 its reverse (120111122), we get a palindrome (341222143).

It can be divided in two parts, 22111 and 1021, that added together give a palindrome (23132).

The spelling of 221111021 in words is "two hundred twenty-one million, one hundred eleven thousand, twenty-one".