18212981 has 2 divisors, whose sum is σ = 18212982. Its totient is φ = 18212980.

The previous prime is 18212969. The next prime is 18212993. The reversal of 18212981 is 18921281.

It is a balanced prime because it is at equal distance from previous prime (18212969) and next prime (18212993).

It can be written as a sum of positive squares in only one way, i.e., 17926756 + 286225 = 4234^2 + 535^2 .

It is a cyclic number.

It is not a de Polignac number, because 18212981 - 2¹⁰ = 18211957 is a prime.

It is a super-2 number, since 2×18212981² = 663425353812722, 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 (18212081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9106490 + 9106491.

It is an arithmetic number, because the mean of its divisors is an integer number (9106491).

Almost surely, 2^18212981 is an apocalyptic number.

It is an amenable number.

18212981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18212981 is an equidigital number, since it uses as much as digits as its factorization.

18212981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 32.

The square root of 18212981 is about 4267.6669270223. Note that the first 3 decimals coincide. The cubic root of 18212981 is about 263.1037338918.

The spelling of 18212981 in words is "eighteen million, two hundred twelve thousand, nine hundred eighty-one".