18266981 has 2 divisors, whose sum is σ = 18266982. Its totient is φ = 18266980.

The previous prime is 18266957. The next prime is 18267001. The reversal of 18266981 is 18966281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17986081 + 280900 = 4241^2 + 530^2 .

It is an emirp because it is prime and its reverse (18966281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18266981 - 2²² = 14072677 is a prime.

It is a super-2 number, since 2×18266981² = 667365189708722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18266081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9133490 + 9133491.

It is an arithmetic number, because the mean of its divisors is an integer number (9133491).

Almost surely, 2^18266981 is an apocalyptic number.

It is an amenable number.

18266981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18266981 is an equidigital number, since it uses as much as digits as its factorization.

18266981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 41.

The square root of 18266981 is about 4273.9888862747. The cubic root of 18266981 is about 263.3635043499.

The spelling of 18266981 in words is "eighteen million, two hundred sixty-six thousand, nine hundred eighty-one".