66161571840 has 1440 divisors, whose sum is σ = 300608249760. Its totient is φ = 13352435712.

The previous prime is 66161571823. The next prime is 66161571841. The reversal of 66161571840 is 4817516166.

66161571840 is a `hidden beast` number, since 6 + 616 + 15 + 7 + 18 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1440).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66161571841) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 2876590069 + ... + 2876590091.

It is an arithmetic number, because the mean of its divisors is an integer number (208755729).

Almost surely, 2^66161571840 is an apocalyptic number.

66161571840 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 66161571840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150304124880).

66161571840 is an abundant number, since it is smaller than the sum of its proper divisors (234446677920).

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

66161571840 is a wasteful number, since it uses less digits than its factorization.

66161571840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 66161571840 in words is "sixty-six billion, one hundred sixty-one million, five hundred seventy-one thousand, eight hundred forty".