1002001021 has 4 divisors (see below), whose sum is σ = 1145144032. Its totient is φ = 858858012.

The previous prime is 1002000997. The next prime is 1002001057. The reversal of 1002001021 is 1201002001.

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 a de Polignac number, because none of the positive numbers 2^k-1002001021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (7), and also a Moran number because the ratio is a prime number: 143143003 = 1002001021 / (1 + 0 + 0 + 2 + 0 + 0 + 1 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1002000995 and 1002001013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1002002021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71571495 + ... + 71571508.

It is an arithmetic number, because the mean of its divisors is an integer number (286286008).

Almost surely, 2^1002001021 is an apocalyptic number.

It is an amenable number.

1002001021 is a deficient number, since it is larger than the sum of its proper divisors (143143011).

1002001021 is an equidigital number, since it uses as much as digits as its factorization.

1002001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143143010.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 1002001021 is about 31654.3997099929. The cubic root of 1002001021 is about 1000.6665625956. Note that the first 3 decimals are identical.

Adding to 1002001021 its reverse (1201002001), we get a palindrome (2203003022).

The spelling of 1002001021 in words is "one billion, two million, one thousand, twenty-one".