18539640 has 144 divisors (see below), whose sum is σ = 70157880. Its totient is φ = 4233600.

The previous prime is 18539621. The next prime is 18539657. The reversal of 18539640 is 4693581.

18539640 is a `hidden beast` number, since 1 + 8 + 5 + 3 + 9 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 18539595 and 18539604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 17115 + ... + 18165.

Almost surely, 2^18539640 is an apocalyptic number.

18539640 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 18539640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35078940).

18539640 is an abundant number, since it is smaller than the sum of its proper divisors (51618240).

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

18539640 is a wasteful number, since it uses less digits than its factorization.

18539640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1082 (or 1068 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 18539640 is about 4305.7682241384. The cubic root of 18539640 is about 264.6673885637.

The spelling of 18539640 in words is "eighteen million, five hundred thirty-nine thousand, six hundred forty".