18729840 has 40 divisors (see below), whose sum is σ = 58063248. Its totient is φ = 4994560.

The previous prime is 18729817. The next prime is 18729847. The reversal of 18729840 is 4892781.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18729847) 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 7 ways as a sum of consecutive naturals, for example, 38781 + ... + 39260.

Almost surely, 2^18729840 is an apocalyptic number.

18729840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18729840 is an abundant number, since it is smaller than the sum of its proper divisors (39333408).

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

18729840 is a wasteful number, since it uses less digits than its factorization.

18729840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78057 (or 78051 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 18729840 is about 4327.7985165671. The cubic root of 18729840 is about 265.5693939427.

The spelling of 18729840 in words is "eighteen million, seven hundred twenty-nine thousand, eight hundred forty".