18781994 has 64 divisors (see below), whose sum is σ = 38016000. Its totient is φ = 6879600.

The previous prime is 18781993. The next prime is 18782009. The reversal of 18781994 is 49918781.

It is not an unprimeable number, because it can be changed into a prime (18781993) 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 31 ways as a sum of consecutive naturals, for example, 143309 + ... + 143439.

It is an arithmetic number, because the mean of its divisors is an integer number (594000).

Almost surely, 2^18781994 is an apocalyptic number.

18781994 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

18781994 is an abundant number, since it is smaller than the sum of its proper divisors (19234006).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18781994 is a wasteful number, since it uses less digits than its factorization.

18781994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184 (or 170 counting only the distinct ones).

The product of its digits is 145152, while the sum is 47.

The square root of 18781994 is about 4333.8197932078. The cubic root of 18781994 is about 265.8156617566.

The spelling of 18781994 in words is "eighteen million, seven hundred eighty-one thousand, nine hundred ninety-four".