20021000999 has 4 divisors (see below), whose sum is σ = 20085377520. Its totient is φ = 19956624480.

The previous prime is 20021000981. The next prime is 20021001029. The reversal of 20021000999 is 99900012002.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021000999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021000899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32187794 + ... + 32188415.

It is an arithmetic number, because the mean of its divisors is an integer number (5021344380).

Almost surely, 2^20021000999 is an apocalyptic number.

20021000999 is a deficient number, since it is larger than the sum of its proper divisors (64376521).

20021000999 is an equidigital number, since it uses as much as digits as its factorization.

20021000999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64376520.

The product of its (nonzero) digits is 2916, while the sum is 32.

It can be divided in two parts, 2002 and 1000999, that added together give a palindrome (1003001).

The spelling of 20021000999 in words is "twenty billion, twenty-one million, nine hundred ninety-nine", and thus it is an aban number.