1000021 has 4 divisors (see below), whose sum is σ = 1090944. Its totient is φ = 909100.

The previous prime is 1000003. The next prime is 1000033. The reversal of 1000021 is 1200001.

1000021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 1000021 - 2¹¹ = 997973 is a prime.

It is a Duffinian number.

1000021 is a modest number, since divided by 21 gives 1 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1000081) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45445 + ... + 45466.

It is an arithmetic number, because the mean of its divisors is an integer number (272736).

2^1000021 is an apocalyptic number.

1000021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1000021 is a deficient number, since it is larger than the sum of its proper divisors (90923).

1000021 is an equidigital number, since it uses as much as digits as its factorization.

1000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90922.

The product of its (nonzero) digits is 2, while the sum is 4.

The square root of 1000021 is about 1000.0104999449. The cubic root of 1000021 is about 100.0006999951. Note that the first 3 decimals are identical.

Adding to 1000021 its reverse (1200001), we get a palindrome (2200022).

Multiplying 1000021 by its reverse (1200001), we get a palindrome (1200026200021).

The spelling of 1000021 in words is "one million, twenty-one", and thus it is an aban number and an uban number.