1002001221 has 12 divisors (see below), whose sum is σ = 1558668748. Its totient is φ = 616616064.

The previous prime is 1002001219. The next prime is 1002001237. The reversal of 1002001221 is 1221002001.

It can be written as a sum of positive squares in 2 ways, for example, as 266832225 + 735168996 = 16335^2 + 27114^2 .

It is not a de Polignac number, because 1002001221 - 2¹ = 1002001219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

1002001221 is a modest number, since divided by 1221 gives 1002 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1002001211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4281940 + ... + 4282173.

Almost surely, 2^1002001221 is an apocalyptic number.

It is an amenable number.

1002001221 is a deficient number, since it is larger than the sum of its proper divisors (556667527).

1002001221 is a wasteful number, since it uses less digits than its factorization.

1002001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8564132 (or 8564129 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1002001221 is about 31654.4028691113. The cubic root of 1002001221 is about 1000.6666291735. Note that the first 4 decimals are identical.

Adding to 1002001221 its reverse (1221002001), we get a palindrome (2223003222).

The spelling of 1002001221 in words is "one billion, two million, one thousand, two hundred twenty-one".