2021000021 has 4 divisors (see below), whose sum is σ = 2031156000. Its totient is φ = 2010844044.

The previous prime is 2021000017. The next prime is 2021000027. The reversal of 2021000021 is 1200001202.

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 2021000021 - 2² = 2021000017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2020999972 and 2021000008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021000027) 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, 5077691 + ... + 5078088.

It is an arithmetic number, because the mean of its divisors is an integer number (507789000).

Almost surely, 2^2021000021 is an apocalyptic number.

It is an amenable number.

2021000021 is a deficient number, since it is larger than the sum of its proper divisors (10155979).

2021000021 is a wasteful number, since it uses less digits than its factorization.

2021000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10155978.

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

The square root of 2021000021 is about 44955.5338195422. The cubic root of 2021000021 is about 1264.3154333222.

Adding to 2021000021 its reverse (1200001202), we get a palindrome (3221001223).

The spelling of 2021000021 in words is "two billion, twenty-one million, twenty-one", and thus it is an aban number and an uban number.