1001002001 has 2 divisors, whose sum is σ = 1001002002. Its totient is φ = 1001002000.

The previous prime is 1001001923. The next prime is 1001002049. The reversal of 1001002001 is 1002001001.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 941016976 + 59985025 = 30676^2 + 7745^2 .

It is a cyclic number.

It is not a de Polignac number, because 1001002001 - 2¹⁰ = 1001000977 is a prime.

It is not a weakly prime, because it can be changed into another prime (1001005001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500501000 + 500501001.

It is an arithmetic number, because the mean of its divisors is an integer number (500501001).

Almost surely, 2^1001002001 is an apocalyptic number.

It is an amenable number.

1001002001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001002001 is an equidigital number, since it uses as much as digits as its factorization.

1001002001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 1001002001 is about 31638.6156618775. The cubic root of 1001002001 is about 1000.3338888392. Note that the first 3 decimals are identical.

Adding to 1001002001 its reverse (1002001001), we get a palindrome (2003003002).

It can be divided in two parts, 100 and 1002001, that multiplied together give a square (100200100 = 10010²).

The spelling of 1001002001 in words is "one billion, one million, two thousand, one".