18681890 has 8 divisors (see below), whose sum is σ = 33627420. Its totient is φ = 7472752.

The previous prime is 18681863. The next prime is 18681899. The reversal of 18681890 is 9818681.

It can be written as a sum of positive squares in 2 ways, for example, as 17884441 + 797449 = 4229^2 + 893^2 .

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

It is not an unprimeable number, because it can be changed into a prime (18681899) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 934085 + ... + 934104.

Almost surely, 2^18681890 is an apocalyptic number.

18681890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18681890 is a deficient number, since it is larger than the sum of its proper divisors (14945530).

18681890 is a wasteful number, since it uses less digits than its factorization.

18681890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1868196.

The product of its (nonzero) digits is 27648, while the sum is 41.

The square root of 18681890 is about 4322.2551983889. The cubic root of 18681890 is about 265.3425734488.

The spelling of 18681890 in words is "eighteen million, six hundred eighty-one thousand, eight hundred ninety".