11999939981 has 2 divisors, whose sum is σ = 11999939982. Its totient is φ = 11999939980.

The previous prime is 11999939977. The next prime is 11999939989. The reversal of 11999939981 is 18993999911.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10922131081 + 1077808900 = 104509^2 + 32830^2 .

It is a cyclic number.

It is not a de Polignac number, because 11999939981 - 2² = 11999939977 is a prime.

It is a super-2 number, since 2×11999939981² (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 (11999939989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5999969990 + 5999969991.

It is an arithmetic number, because the mean of its divisors is an integer number (5999969991).

Almost surely, 2^11999939981 is an apocalyptic number.

It is an amenable number.

11999939981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11999939981 is an equidigital number, since it uses as much as digits as its factorization.

11999939981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12754584, while the sum is 68.

The spelling of 11999939981 in words is "eleven billion, nine hundred ninety-nine million, nine hundred thirty-nine thousand, nine hundred eighty-one".