18998640 has 60 divisors (see below), whose sum is σ = 63806184. Its totient is φ = 5066112.

The previous prime is 18998611. The next prime is 18998641. The reversal of 18998640 is 4689981.

It is a tau number, because it is divible by the number of its divisors (60).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18998641) 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 11 ways as a sum of consecutive naturals, for example, 12474 + ... + 13913.

Almost surely, 2^18998640 is an apocalyptic number.

18998640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18998640 is an abundant number, since it is smaller than the sum of its proper divisors (44807544).

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

18998640 is a wasteful number, since it uses less digits than its factorization.

18998640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26406 (or 26397 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 18998640 is about 4358.7429380499. The cubic root of 18998640 is about 266.8337980076.

The spelling of 18998640 in words is "eighteen million, nine hundred ninety-eight thousand, six hundred forty".