18947881 has 8 divisors (see below), whose sum is σ = 19445184. Its totient is φ = 18456720.

The previous prime is 18947879. The next prime is 18947897. The reversal of 18947881 is 18874981.

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 18947881 - 2¹ = 18947879 is a prime.

It is a super-2 number, since 2×18947881² = 718044388780322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18947861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5076 + ... + 7978.

It is an arithmetic number, because the mean of its divisors is an integer number (2430648).

Almost surely, 2^18947881 is an apocalyptic number.

It is an amenable number.

18947881 is a deficient number, since it is larger than the sum of its proper divisors (497303).

18947881 is a wasteful number, since it uses less digits than its factorization.

18947881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3071.

The product of its digits is 129024, while the sum is 46.

The square root of 18947881 is about 4352.9163787052. The cubic root of 18947881 is about 266.5959512144.

Subtracting from 18947881 its reverse (18874981), we obtain a square (72900 = 270²).

The spelling of 18947881 in words is "eighteen million, nine hundred forty-seven thousand, eight hundred eighty-one".