18643840 has 32 divisors (see below), whose sum is σ = 44571960. Its totient is φ = 7457280.

The previous prime is 18643837. The next prime is 18643843. The reversal of 18643840 is 4834681.

It is an interprime number because it is at equal distance from previous prime (18643837) and next prime (18643843).

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 18643796 and 18643805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18643843) 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 3 ways as a sum of consecutive naturals, for example, 13926 + ... + 15205.

Almost surely, 2^18643840 is an apocalyptic number.

18643840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18643840 is an abundant number, since it is smaller than the sum of its proper divisors (25928120).

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

18643840 is an equidigital number, since it uses as much as digits as its factorization.

18643840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29150 (or 29138 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 34.

The square root of 18643840 is about 4317.8513174958. The cubic root of 18643840 is about 265.1623071203.

The spelling of 18643840 in words is "eighteen million, six hundred forty-three thousand, eight hundred forty".