18955981 has 12 divisors (see below), whose sum is σ = 21349692. Its totient is φ = 16808000.

The previous prime is 18955957. The next prime is 18955987.

18955981 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 2 ways, for example, as 8497225 + 10458756 = 2915^2 + 3234^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18955981 is a prime.

It is a super-2 number, since 2×18955981² = 718658431344722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18955987) 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 in 11 ways as a sum of consecutive naturals, for example, 3051 + ... + 6871.

It is an arithmetic number, because the mean of its divisors is an integer number (1779141).

Almost surely, 2^18955981 is an apocalyptic number.

18955981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18955981 is a deficient number, since it is larger than the sum of its proper divisors (2393711).

18955981 is a wasteful number, since it uses less digits than its factorization.

18955981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3884 (or 3873 counting only the distinct ones).

The product of its digits is 129600, while the sum is 46.

The square root of 18955981 is about 4353.8466899972. The cubic root of 18955981 is about 266.6339346978.

The spelling of 18955981 in words is "eighteen million, nine hundred fifty-five thousand, nine hundred eighty-one".