1001221220221 has 4 divisors (see below), whose sum is σ = 1003051606912. Its totient is φ = 999390833532.

The previous prime is 1001221220123. The next prime is 1001221220231. The reversal of 1001221220221 is 1220221221001.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1001221220221 - 2¹³ = 1001221212029 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1001221220195 and 1001221220204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001221220231) 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, 915192525 + ... + 915193618.

It is an arithmetic number, because the mean of its divisors is an integer number (250762901728).

Almost surely, 2^{1001221220221} is an apocalyptic number.

It is an amenable number.

1001221220221 is a deficient number, since it is larger than the sum of its proper divisors (1830386691).

1001221220221 is an equidigital number, since it uses as much as digits as its factorization.

1001221220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1830386690.

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

Adding to 1001221220221 its reverse (1220221221001), we get a palindrome (2221442441222).

The spelling of 1001221220221 in words is "one trillion, one billion, two hundred twenty-one million, two hundred twenty thousand, two hundred twenty-one".