11220001981 has 2 divisors, whose sum is σ = 11220001982. Its totient is φ = 11220001980.

The previous prime is 11220001973. The next prime is 11220002041. The reversal of 11220001981 is 18910002211.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10148749081 + 1071252900 = 100741^2 + 32730^2 .

It is an emirp because it is prime and its reverse (18910002211) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11220001981 - 2³ = 11220001973 is a prime.

It is a super-2 number, since 2×11220001981² (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 (11220011981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5610000990 + 5610000991.

It is an arithmetic number, because the mean of its divisors is an integer number (5610000991).

Almost surely, 2^11220001981 is an apocalyptic number.

It is an amenable number.

11220001981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11220001981 is an equidigital number, since it uses as much as digits as its factorization.

11220001981 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 25.

The spelling of 11220001981 in words is "eleven billion, two hundred twenty million, one thousand, nine hundred eighty-one".