18491271840 has 192 divisors, whose sum is σ = 66807659520. Its totient is φ = 4771906560.

The previous prime is 18491271791. The next prime is 18491271847. The reversal of 18491271840 is 4817219481.

18491271840 is a `hidden beast` number, since 18 + 491 + 2 + 71 + 84 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (18491271847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 64882 + ... + 202958.

It is an arithmetic number, because the mean of its divisors is an integer number (347956560).

Almost surely, 2^18491271840 is an apocalyptic number.

18491271840 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 18491271840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33403829760).

18491271840 is an abundant number, since it is smaller than the sum of its proper divisors (48316387680).

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

18491271840 is a wasteful number, since it uses less digits than its factorization.

18491271840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138132 (or 138118 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The spelling of 18491271840 in words is "eighteen billion, four hundred ninety-one million, two hundred seventy-one thousand, eight hundred forty".