18988981 has 8 divisors (see below), whose sum is σ = 20746944. Its totient is φ = 17236320.

The previous prime is 18988967. The next prime is 18989023.

18988981 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18988981 is a prime.

It is a super-2 number, since 2×18988981² = 721162798836722, 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 (18928981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12400 + ... + 13846.

It is an arithmetic number, because the mean of its divisors is an integer number (2593368).

Almost surely, 2^18988981 is an apocalyptic number.

18988981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18988981 is a deficient number, since it is larger than the sum of its proper divisors (1757963).

18988981 is a wasteful number, since it uses less digits than its factorization.

18988981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2651.

The product of its digits is 331776, while the sum is 52.

The square root of 18988981 is about 4357.6347942433. The cubic root of 18988981 is about 266.7885704798.

The spelling of 18988981 in words is "eighteen million, nine hundred eighty-eight thousand, nine hundred eighty-one".