1001221221 has 64 divisors (see below), whose sum is σ = 1841043456. Its totient is φ = 467078400.

The previous prime is 1001221187. The next prime is 1001221223. The reversal of 1001221221 is 1221221001.

It is not a de Polignac number, because 1001221221 - 2⁶ = 1001221157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1001221197 and 1001221206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001221223) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 106606 + ... + 115616.

It is an arithmetic number, because the mean of its divisors is an integer number (28766304).

Almost surely, 2^1001221221 is an apocalyptic number.

1001221221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1001221221 is a deficient number, since it is larger than the sum of its proper divisors (839822235).

1001221221 is a wasteful number, since it uses less digits than its factorization.

1001221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9082.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 1001221221 is about 31642.0799095129. The cubic root of 1001221221 is about 1000.4069080700.

Adding to 1001221221 its reverse (1221221001), we get a palindrome (2222442222).

It can be divided in two parts, 1001 and 221221, that added together give a palindrome (222222).

The spelling of 1001221221 in words is "one billion, one million, two hundred twenty-one thousand, two hundred twenty-one".