18881681 has 8 divisors (see below), whose sum is σ = 23239104. Its totient is φ = 14939280.

The previous prime is 18881677. The next prime is 18881683. The reversal of 18881681 is 18618881.

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 18881681 - 2² = 18881677 is a prime.

It is a super-2 number, since 2×18881681² = 713035754771522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18881683) 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, 103655 + ... + 103836.

It is an arithmetic number, because the mean of its divisors is an integer number (2904888).

Almost surely, 2^18881681 is an apocalyptic number.

It is an amenable number.

18881681 is a deficient number, since it is larger than the sum of its proper divisors (4357423).

18881681 is a wasteful number, since it uses less digits than its factorization.

18881681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207511.

The product of its digits is 24576, while the sum is 41.

The square root of 18881681 is about 4345.3056279162. The cubic root of 18881681 is about 266.2851117852.

The spelling of 18881681 in words is "eighteen million, eight hundred eighty-one thousand, six hundred eighty-one".