10001001001221 has 6 divisors (see below), whose sum is σ = 14445890335110. Its totient is φ = 6667334000808.

The previous prime is 10001001001217. The next prime is 10001001001223. The reversal of 10001001001221 is 12210010010001.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 6423943702500 + 3577057298721 = 2534550^2 + 1891311^2 .

It is not a de Polignac number, because 10001001001221 - 2² = 10001001001217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 1111222333469 = 10001001001221 / (1 + 0 + 0 + 0 + 1 + 0 + 0 + 1 + 0 + 0 + 1 + 2 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10001001001223) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 555611166726 + ... + 555611166743.

It is an arithmetic number, because the mean of its divisors is an integer number (2407648389185).

Almost surely, 2^{10001001001221} is an apocalyptic number.

It is an amenable number.

10001001001221 is a deficient number, since it is larger than the sum of its proper divisors (4444889333889).

10001001001221 is a wasteful number, since it uses less digits than its factorization.

10001001001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1111222333475 (or 1111222333472 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 10001001001221 its reverse (12210010010001), we get a palindrome (22211011011222).

The spelling of 10001001001221 in words is "ten trillion, one billion, one million, one thousand, two hundred twenty-one".