1002020021 has 4 divisors (see below), whose sum is σ = 1002409344. Its totient is φ = 1001630700.

The previous prime is 1002020017. The next prime is 1002020027. The reversal of 1002020021 is 1200202001.

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 1002020021 - 2² = 1002020017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1002019990 and 1002020008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1002020027) 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, 190775 + ... + 195956.

It is an arithmetic number, because the mean of its divisors is an integer number (250602336).

Almost surely, 2^1002020021 is an apocalyptic number.

It is an amenable number.

1002020021 is a deficient number, since it is larger than the sum of its proper divisors (389323).

1002020021 is an equidigital number, since it uses as much as digits as its factorization.

1002020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389322.

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

The square root of 1002020021 is about 31654.6998248285. The cubic root of 1002020021 is about 1000.6728874543.

Adding to 1002020021 its reverse (1200202001), we get a palindrome (2202222022).

The spelling of 1002020021 in words is "one billion, two million, twenty thousand, twenty-one".