20110019981 has 2 divisors, whose sum is σ = 20110019982. Its totient is φ = 20110019980.

The previous prime is 20110019971. The next prime is 20110020037. The reversal of 20110019981 is 18991001102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18498720100 + 1611299881 = 136010^2 + 40141^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20110019981 is a prime.

It is a super-2 number, since 2×20110019981² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20110019911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055009990 + 10055009991.

It is an arithmetic number, because the mean of its divisors is an integer number (10055009991).

Almost surely, 2^20110019981 is an apocalyptic number.

It is an amenable number.

20110019981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20110019981 is an equidigital number, since it uses as much as digits as its factorization.

20110019981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 32.

The spelling of 20110019981 in words is "twenty billion, one hundred ten million, nineteen thousand, nine hundred eighty-one".