18280981 has 2 divisors, whose sum is σ = 18280982. Its totient is φ = 18280980.

The previous prime is 18280963. The next prime is 18280993. The reversal of 18280981 is 18908281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13727025 + 4553956 = 3705^2 + 2134^2 .

It is a cyclic number.

It is not a de Polignac number, because 18280981 - 2⁵ = 18280949 is a prime.

It is a super-2 number, since 2×18280981² = 668388532644722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18280981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18280901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9140490 + 9140491.

It is an arithmetic number, because the mean of its divisors is an integer number (9140491).

Almost surely, 2^18280981 is an apocalyptic number.

It is an amenable number.

18280981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18280981 is an equidigital number, since it uses as much as digits as its factorization.

18280981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 18280981 is about 4275.6263868584. The cubic root of 18280981 is about 263.4307686581.

The spelling of 18280981 in words is "eighteen million, two hundred eighty thousand, nine hundred eighty-one".