66001681440 has 192 divisors, whose sum is σ = 231862417920. Its totient is φ = 17535191040.

The previous prime is 66001681411. The next prime is 66001681477. The reversal of 66001681440 is 4418610066.

66001681440 is a `hidden beast` number, since 6 + 600 + 1 + 6 + 8 + 1 + 4 + 40 = 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 = 66001681395 and 66001681404.

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, 1142532 + ... + 1198908.

It is an arithmetic number, because the mean of its divisors is an integer number (1207616760).

Almost surely, 2^66001681440 is an apocalyptic number.

66001681440 is a gapful number since it is divisible by the number (60) 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 66001681440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115931208960).

66001681440 is an abundant number, since it is smaller than the sum of its proper divisors (165860736480).

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

66001681440 is a wasteful number, since it uses less digits than its factorization.

66001681440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56672 (or 56658 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The spelling of 66001681440 in words is "sixty-six billion, one million, six hundred eighty-one thousand, four hundred forty".