20201221993 has 2 divisors, whose sum is σ = 20201221994. Its totient is φ = 20201221992.

The previous prime is 20201221981. The next prime is 20201222017. The reversal of 20201221993 is 39912210202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20194399449 + 6822544 = 142107^2 + 2612^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20201221993 is a prime.

It is not a weakly prime, because it can be changed into another prime (20201221913) 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 as a sum of consecutive naturals, namely, 10100610996 + 10100610997.

It is an arithmetic number, because the mean of its divisors is an integer number (10100610997).

Almost surely, 2^20201221993 is an apocalyptic number.

It is an amenable number.

20201221993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20201221993 is an equidigital number, since it uses as much as digits as its factorization.

20201221993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 31.

The spelling of 20201221993 in words is "twenty billion, two hundred one million, two hundred twenty-one thousand, nine hundred ninety-three".