18515640 has 192 divisors, whose sum is σ = 66407040. Its totient is φ = 4093440.

The previous prime is 18515639. The next prime is 18515657. The reversal of 18515640 is 4651581.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 18515598 and 18515607.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 223039 + ... + 223121.

It is an arithmetic number, because the mean of its divisors is an integer number (345870).

Almost surely, 2^18515640 is an apocalyptic number.

18515640 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 18515640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33203520).

18515640 is an abundant number, since it is smaller than the sum of its proper divisors (47891400).

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

18515640 is a wasteful number, since it uses less digits than its factorization.

18515640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 30.

The square root of 18515640 is about 4302.9803624930. The cubic root of 18515640 is about 264.5531331944.

The spelling of 18515640 in words is "eighteen million, five hundred fifteen thousand, six hundred forty".