221211220121 has 8 divisors (see below), whose sum is σ = 236296422504. Its totient is φ = 206356326400.

The previous prime is 221211220099. The next prime is 221211220123. The reversal of 221211220121 is 121022112122.

It can be written as a sum of positive squares in 4 ways, for example, as 51911065600 + 169300154521 = 227840^2 + 411461^2 .

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 221211220121 - 2³⁴ = 204031350937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

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 221211220121.

It is not an unprimeable number, because it can be changed into a prime (221211220123) 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, 57575180 + ... + 57579021.

It is an arithmetic number, because the mean of its divisors is an integer number (29537052813).

Almost surely, 2^221211220121 is an apocalyptic number.

It is an amenable number.

221211220121 is a deficient number, since it is larger than the sum of its proper divisors (15085202383).

221211220121 is a wasteful number, since it uses less digits than its factorization.

221211220121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115154331.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 221211220121 its reverse (121022112122), we get a palindrome (342233332243).

The spelling of 221211220121 in words is "two hundred twenty-one billion, two hundred eleven million, two hundred twenty thousand, one hundred twenty-one".