20210000021 has 4 divisors (see below), whose sum is σ = 20214324000. Its totient is φ = 20205676044.

The previous prime is 20209999991. The next prime is 20210000023. The reversal of 20210000021 is 12000001202.

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 20210000021 - 2¹⁴ = 20209983637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20209999963 and 20210000008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20210000023) 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, 2154971 + ... + 2164328.

It is an arithmetic number, because the mean of its divisors is an integer number (5053581000).

Almost surely, 2^20210000021 is an apocalyptic number.

It is an amenable number.

20210000021 is a deficient number, since it is larger than the sum of its proper divisors (4323979).

20210000021 is an equidigital number, since it uses as much as digits as its factorization.

20210000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4323978.

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

Adding to 20210000021 its reverse (12000001202), we get a palindrome (32210001223).

The spelling of 20210000021 in words is "twenty billion, two hundred ten million, twenty-one", and thus it is an aban number.