20019999991 has 2 divisors, whose sum is σ = 20019999992. Its totient is φ = 20019999990.

The previous prime is 20019999973. The next prime is 20020000073. The reversal of 20019999991 is 19999991002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20019999991 - 2⁷ = 20019999863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20019999191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10009999995 + 10009999996.

It is an arithmetic number, because the mean of its divisors is an integer number (10009999996).

Almost surely, 2^20019999991 is an apocalyptic number.

20019999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20019999991 is an equidigital number, since it uses as much as digits as its factorization.

20019999991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1062882, while the sum is 58.

The spelling of 20019999991 in words is "twenty billion, nineteen million, nine hundred ninety-nine thousand, nine hundred ninety-one".