221021123 has 4 divisors (see below), whose sum is σ = 221379960. Its totient is φ = 220662288.

The previous prime is 221021111. The next prime is 221021137. The reversal of 221021123 is 321120122.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 221021123 - 2¹⁰ = 221020099 is a prime.

It is a super-2 number, since 2×221021123² = 97700673624362258, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221021098 and 221021107.

It is not an unprimeable number, because it can be changed into a prime (221021173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 178493 + ... + 179726.

It is an arithmetic number, because the mean of its divisors is an integer number (55344990).

Almost surely, 2^221021123 is an apocalyptic number.

221021123 is a deficient number, since it is larger than the sum of its proper divisors (358837).

221021123 is an equidigital number, since it uses as much as digits as its factorization.

221021123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358836.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 221021123 is about 14866.7791737148. The cubic root of 221021123 is about 604.6136211997.

Adding to 221021123 its reverse (321120122), we get a palindrome (542141245).

The spelling of 221021123 in words is "two hundred twenty-one million, twenty-one thousand, one hundred twenty-three".