11918981 has 2 divisors, whose sum is σ = 11918982. Its totient is φ = 11918980.

The previous prime is 11918941. The next prime is 11918993. The reversal of 11918981 is 18981911.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11730625 + 188356 = 3425^2 + 434^2 .

It is a cyclic number.

It is not a de Polignac number, because 11918981 - 2¹⁰ = 11917957 is a prime.

It is a super-2 number, since 2×11918981² = 284124216156722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11918941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5959490 + 5959491.

It is an arithmetic number, because the mean of its divisors is an integer number (5959491).

Almost surely, 2^11918981 is an apocalyptic number.

It is an amenable number.

11918981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11918981 is an equidigital number, since it uses as much as digits as its factorization.

11918981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 38.

The square root of 11918981 is about 3452.3877244597. The cubic root of 11918981 is about 228.4264423345.

The spelling of 11918981 in words is "eleven million, nine hundred eighteen thousand, nine hundred eighty-one".