18917440 has 56 divisors (see below), whose sum is σ = 46524672. Its totient is φ = 7319040.

The previous prime is 18917417. The next prime is 18917467. The reversal of 18917440 is 4471981.

It is a junction number, because it is equal to n+sod(n) for n = 18917396 and 18917405.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8967 + ... + 10873.

Almost surely, 2^18917440 is an apocalyptic number.

18917440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18917440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23262336).

18917440 is an abundant number, since it is smaller than the sum of its proper divisors (27607232).

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

18917440 is a wasteful number, since it uses less digits than its factorization.

18917440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1955 (or 1945 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 18917440 is about 4349.4183519179. The cubic root of 18917440 is about 266.4531067941.

The spelling of 18917440 in words is "eighteen million, nine hundred seventeen thousand, four hundred forty".