18731440 has 160 divisors (see below), whose sum is σ = 55996416. Its totient is φ = 5667840.

The previous prime is 18731437. The next prime is 18731459. The reversal of 18731440 is 4413781.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 18731399 and 18731408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 225639 + ... + 225721.

Almost surely, 2^18731440 is an apocalyptic number.

18731440 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 18731440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27998208).

18731440 is an abundant number, since it is smaller than the sum of its proper divisors (37264976).

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

18731440 is a wasteful number, since it uses less digits than its factorization.

18731440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 18731440 is about 4327.9833641085. The cubic root of 18731440 is about 265.5769558320.

The spelling of 18731440 in words is "eighteen million, seven hundred thirty-one thousand, four hundred forty".