66444840 has 512 divisors, whose sum is σ = 298598400. Its totient is φ = 12718080.

The previous prime is 66444827. The next prime is 66444841. The reversal of 66444840 is 4844466.

66444840 is a `hidden beast` number, since 6 + 644 + 4 + 8 + 4 + 0 = 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 = 66444795 and 66444804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66444841) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1413697 + ... + 1413743.

It is an arithmetic number, because the mean of its divisors is an integer number (583200).

Almost surely, 2^66444840 is an apocalyptic number.

66444840 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 66444840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149299200).

66444840 is an abundant number, since it is smaller than the sum of its proper divisors (232153560).

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

66444840 is a wasteful number, since it uses less digits than its factorization.

66444840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102 (or 92 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 36.

The square root of 66444840 is about 8151.3704369265. The cubic root of 66444840 is about 405.0299017703.

The spelling of 66444840 in words is "sixty-six million, four hundred forty-four thousand, eight hundred forty".