221521123 has 2 divisors, whose sum is σ = 221521124. Its totient is φ = 221521122.

The previous prime is 221521087. The next prime is 221521129. The reversal of 221521123 is 321125122.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221521123 is a prime.

It is a super-2 number, since 2×221521123² = 98143215870362258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221521123.

It is not a weakly prime, because it can be changed into another prime (221521129) 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 as a sum of consecutive naturals, namely, 110760561 + 110760562.

It is an arithmetic number, because the mean of its divisors is an integer number (110760562).

Almost surely, 2^221521123 is an apocalyptic number.

221521123 is a deficient number, since it is larger than the sum of its proper divisors (1).

221521123 is an equidigital number, since it uses as much as digits as its factorization.

221521123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 19.

The square root of 221521123 is about 14883.5856902831. The cubic root of 221521123 is about 605.0692022928.

Adding to 221521123 its reverse (321125122), we get a palindrome (542646245).

The spelling of 221521123 in words is "two hundred twenty-one million, five hundred twenty-one thousand, one hundred twenty-three".