1001211021221 has 4 divisors (see below), whose sum is σ = 1001216453292. Its totient is φ = 1001205589152.

The previous prime is 1001211021211. The next prime is 1001211021257. The reversal of 1001211021221 is 1221201121001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 791228040100 + 209982981121 = 889510^2 + 458239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1001211021221 - 2¹⁴ = 1001211004837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1001211021196 and 1001211021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001211021211) 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, 2429486 + ... + 2811551.

It is an arithmetic number, because the mean of its divisors is an integer number (250304113323).

Almost surely, 2^{1001211021221} is an apocalyptic number.

It is an amenable number.

1001211021221 is a deficient number, since it is larger than the sum of its proper divisors (5432071).

1001211021221 is an equidigital number, since it uses as much as digits as its factorization.

1001211021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5432070.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 1001211021221 its reverse (1221201121001), we get a palindrome (2222412142222).

The spelling of 1001211021221 in words is "one trillion, one billion, two hundred eleven million, twenty-one thousand, two hundred twenty-one".