221231001221 has 4 divisors (see below), whose sum is σ = 221480416992. Its totient is φ = 220981585452.

The previous prime is 221231001197. The next prime is 221231001269. The reversal of 221231001221 is 122100132122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122100132122 = 2 ⋅61050066061.

It is a cyclic number.

It is not a de Polignac number, because 221231001221 - 2²² = 221226806917 is a prime.

It is a super-2 number, since 2×221231001221² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221231001221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221230001221) 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 in 3 ways as a sum of consecutive naturals, for example, 124706555 + ... + 124708328.

It is an arithmetic number, because the mean of its divisors is an integer number (55370104248).

Almost surely, 2^221231001221 is an apocalyptic number.

It is an amenable number.

221231001221 is a deficient number, since it is larger than the sum of its proper divisors (249415771).

221231001221 is an equidigital number, since it uses as much as digits as its factorization.

221231001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249415770.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 221231001221 its reverse (122100132122), we get a palindrome (343331133343).

The spelling of 221231001221 in words is "two hundred twenty-one billion, two hundred thirty-one million, one thousand, two hundred twenty-one".