11001001981 has 2 divisors, whose sum is σ = 11001001982. Its totient is φ = 11001001980.

The previous prime is 11001001933. The next prime is 11001002003. The reversal of 11001001981 is 18910010011.

It is an a-pointer prime, because the next prime (11001002003) can be obtained adding 11001001981 to its sum of digits (22).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10248322756 + 752679225 = 101234^2 + 27435^2 .

It is an emirp because it is prime and its reverse (18910010011) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 18610010011 and 11001001681.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11001001981 is a prime.

It is a super-2 number, since 2×11001001981² (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 (11001001901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5500500990 + 5500500991.

It is an arithmetic number, because the mean of its divisors is an integer number (5500500991).

Almost surely, 2^11001001981 is an apocalyptic number.

It is an amenable number.

11001001981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11001001981 is an equidigital number, since it uses as much as digits as its factorization.

11001001981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 22.

Adding to 11001001981 its reverse (18910010011), we get a palindrome (29911011992).

The spelling of 11001001981 in words is "eleven billion, one million, one thousand, nine hundred eighty-one".