10001211221 has 4 divisors (see below), whose sum is σ = 10245143244. Its totient is φ = 9757279200.

The previous prime is 10001211217. The next prime is 10001211229. The reversal of 10001211221 is 12211210001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12211210001 = 821 ⋅14873581.

It can be written as a sum of positive squares in 2 ways, for example, as 2451339121 + 7549872100 = 49511^2 + 86890^2 .

It is a cyclic number.

It is not a de Polignac number, because 10001211221 - 2² = 10001211217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10001211229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121965950 + ... + 121966031.

It is an arithmetic number, because the mean of its divisors is an integer number (2561285811).

Almost surely, 2^10001211221 is an apocalyptic number.

It is an amenable number.

10001211221 is a deficient number, since it is larger than the sum of its proper divisors (243932023).

10001211221 is an equidigital number, since it uses as much as digits as its factorization.

10001211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243932022.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 10001211221 its reverse (12211210001), we get a palindrome (22212421222).

The spelling of 10001211221 in words is "ten billion, one million, two hundred eleven thousand, two hundred twenty-one".