18989681 has 8 divisors (see below), whose sum is σ = 19386240. Its totient is φ = 18595728.

The previous prime is 18989671. The next prime is 18989687. The reversal of 18989681 is 18698981.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 18989681 - 2¹⁸ = 18727537 is a prime.

It is a super-2 number, since 2×18989681² = 721215968963522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18989687) 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, 21215 + ... + 22091.

It is an arithmetic number, because the mean of its divisors is an integer number (2423280).

Almost surely, 2^18989681 is an apocalyptic number.

It is an amenable number.

18989681 is a deficient number, since it is larger than the sum of its proper divisors (396559).

18989681 is an equidigital number, since it uses as much as digits as its factorization.

18989681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1303.

The product of its digits is 248832, while the sum is 50.

The square root of 18989681 is about 4357.7151123037. The cubic root of 18989681 is about 266.7918486916.

The spelling of 18989681 in words is "eighteen million, nine hundred eighty-nine thousand, six hundred eighty-one".