20021221209971 has 2 divisors, whose sum is σ = 20021221209972. Its totient is φ = 20021221209970.

The previous prime is 20021221209961. The next prime is 20021221210153. The reversal of 20021221209971 is 17990212212002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20021221209971 - 2⁶ = 20021221209907 is a prime.

It is not a weakly prime, because it can be changed into another prime (20021221209961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010610604985 + 10010610604986.

It is an arithmetic number, because the mean of its divisors is an integer number (10010610604986).

Almost surely, 2^{20021221209971} is an apocalyptic number.

20021221209971 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021221209971 is an equidigital number, since it uses as much as digits as its factorization.

20021221209971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 38.

The spelling of 20021221209971 in words is "twenty trillion, twenty-one billion, two hundred twenty-one million, two hundred nine thousand, nine hundred seventy-one".