20021801993 has 2 divisors, whose sum is σ = 20021801994. Its totient is φ = 20021801992.

The previous prime is 20021801977. The next prime is 20021802019. The reversal of 20021801993 is 39910812002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12266005504 + 7755796489 = 110752^2 + 88067^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021801993 - 2⁴ = 20021801977 is a prime.

It is not a weakly prime, because it can be changed into another prime (20021801903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010900996 + 10010900997.

It is an arithmetic number, because the mean of its divisors is an integer number (10010900997).

Almost surely, 2^20021801993 is an apocalyptic number.

It is an amenable number.

20021801993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021801993 is an equidigital number, since it uses as much as digits as its factorization.

20021801993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 35.

The spelling of 20021801993 in words is "twenty billion, twenty-one million, eight hundred one thousand, nine hundred ninety-three".