221220121021 has 8 divisors (see below), whose sum is σ = 224854439000. Its totient is φ = 217586053440.

The previous prime is 221220121009. The next prime is 221220121027. The reversal of 221220121021 is 120121022122.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 21509448921 + 199710672100 = 146661^2 + 446890^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 221220121021 - 2¹⁵ = 221220088253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221220120986 and 221220121004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221220121027) 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, 2741155 + ... + 2820703.

It is an arithmetic number, because the mean of its divisors is an integer number (28106804875).

Almost surely, 2^221220121021 is an apocalyptic number.

It is an amenable number.

221220121021 is a deficient number, since it is larger than the sum of its proper divisors (3634317979).

221220121021 is an equidigital number, since it uses as much as digits as its factorization.

221220121021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125199.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 221220121021 its reverse (120121022122), we get a palindrome (341341143143).

The spelling of 221220121021 in words is "two hundred twenty-one billion, two hundred twenty million, one hundred twenty-one thousand, twenty-one".