221221021 has 8 divisors (see below), whose sum is σ = 252914240. Its totient is φ = 189550368.

The previous prime is 221220997. The next prime is 221221037. The reversal of 221221021 is 120122122.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221221021 - 2¹¹ = 221218973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221220992 and 221221010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221221081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33430 + ... + 39496.

It is an arithmetic number, because the mean of its divisors is an integer number (31614280).

Almost surely, 2^221221021 is an apocalyptic number.

It is an amenable number.

221221021 is a deficient number, since it is larger than the sum of its proper divisors (31693219).

221221021 is an equidigital number, since it uses as much as digits as its factorization.

221221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11283.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 221221021 is about 14873.5006303156. The cubic root of 221221021 is about 604.7958430519.

Adding to 221221021 its reverse (120122122), we get a palindrome (341343143).

The spelling of 221221021 in words is "two hundred twenty-one million, two hundred twenty-one thousand, twenty-one".