66109789440 has 360 divisors, whose sum is σ = 240453833928. Its totient is φ = 17338613760.

The previous prime is 66109789391. The next prime is 66109789469. The reversal of 66109789440 is 4498790166.

It can be written as a sum of positive squares in 4 ways, for example, as 7514809344 + 58594980096 = 86688^2 + 242064^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a super-2 number, since 2×66109789440² (a number of 22 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 6319254 + ... + 6329706.

Almost surely, 2^66109789440 is an apocalyptic number.

66109789440 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 66109789440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120226916964).

66109789440 is an abundant number, since it is smaller than the sum of its proper divisors (174344044488).

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

66109789440 is a wasteful number, since it uses less digits than its factorization.

66109789440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10547 (or 10524 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 54.

The spelling of 66109789440 in words is "sixty-six billion, one hundred nine million, seven hundred eighty-nine thousand, four hundred forty".