11011021201981 has 2 divisors, whose sum is σ = 11011021201982. Its totient is φ = 11011021201980.

The previous prime is 11011021201979. The next prime is 11011021202023. The reversal of 11011021201981 is 18910212011011.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10105621376356 + 905399825625 = 3178934^2 + 951525^2 .

It is a cyclic number.

It is not a de Polignac number, because 11011021201981 - 2¹ = 11011021201979 is a prime.

It is a super-2 number, since 2×11011021201981² (a number of 27 digits) contains 22 as substring.

Together with 11011021201979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11011021201181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5505510600990 + 5505510600991.

It is an arithmetic number, because the mean of its divisors is an integer number (5505510600991).

Almost surely, 2^{11011021201981} is an apocalyptic number.

It is an amenable number.

11011021201981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11011021201981 is an equidigital number, since it uses as much as digits as its factorization.

11011021201981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 28.

Adding to 11011021201981 its reverse (18910212011011), we get a palindrome (29921233212992).

The spelling of 11011021201981 in words is "eleven trillion, eleven billion, twenty-one million, two hundred one thousand, nine hundred eighty-one".