20021021209 has 24 divisors (see below), whose sum is σ = 24207809472. Its totient is φ = 16216733280.

The previous prime is 20021021203. The next prime is 20021021249. The reversal of 20021021209 is 90212012002.

It is not a de Polignac number, because 20021021209 - 2⁵ = 20021021177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20021021203) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 274779 + ... + 339919.

It is an arithmetic number, because the mean of its divisors is an integer number (1008658728).

Almost surely, 2^20021021209 is an apocalyptic number.

It is an amenable number.

20021021209 is a deficient number, since it is larger than the sum of its proper divisors (4186788263).

20021021209 is an equidigital number, since it uses as much as digits as its factorization.

20021021209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65277 (or 65254 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

The spelling of 20021021209 in words is "twenty billion, twenty-one million, twenty-one thousand, two hundred nine".