18538478640 has 320 divisors, whose sum is σ = 71909683200. Its totient is φ = 4349030400.

The previous prime is 18538478639. The next prime is 18538478641. The reversal of 18538478640 is 4687483581.

18538478640 is a `hidden beast` number, since 1 + 8 + 538 + 47 + 8 + 64 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (18538478639) and next prime (18538478641).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (18538478641) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 723976 + ... + 749144.

It is an arithmetic number, because the mean of its divisors is an integer number (224717760).

Almost surely, 2^18538478640 is an apocalyptic number.

18538478640 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 18538478640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35954841600).

18538478640 is an abundant number, since it is smaller than the sum of its proper divisors (53371204560).

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

18538478640 is a wasteful number, since it uses less digits than its factorization.

18538478640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25233 (or 25221 counting only the distinct ones).

The product of its (nonzero) digits is 5160960, while the sum is 54.

The spelling of 18538478640 in words is "eighteen billion, five hundred thirty-eight million, four hundred seventy-eight thousand, six hundred forty".