20000999981 has 2 divisors, whose sum is σ = 20000999982. Its totient is φ = 20000999980.

The previous prime is 20000999927. The next prime is 20000999999. The reversal of 20000999981 is 18999900002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18423718756 + 1577281225 = 135734^2 + 39715^2 .

It is a cyclic number.

It is not a de Polignac number, because 20000999981 - 2⁶ = 20000999917 is a prime.

It is a super-2 number, since 2×20000999981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20000999911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000499990 + 10000499991.

It is an arithmetic number, because the mean of its divisors is an integer number (10000499991).

Almost surely, 2^20000999981 is an apocalyptic number.

It is an amenable number.

20000999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20000999981 is an equidigital number, since it uses as much as digits as its factorization.

20000999981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 104976, while the sum is 47.

The spelling of 20000999981 in words is "twenty billion, nine hundred ninety-nine thousand, nine hundred eighty-one".