66801644 has 72 divisors (see below), whose sum is σ = 152490240. Its totient is φ = 25002432.

The previous prime is 66801601. The next prime is 66801659. The reversal of 66801644 is 44610866.

It is a super-2 number, since 2×66801644² = 8924919282205472, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 89537 + ... + 90279.

It is an arithmetic number, because the mean of its divisors is an integer number (2117920).

Almost surely, 2^66801644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66801644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (76245120).

66801644 is an abundant number, since it is smaller than the sum of its proper divisors (85688596).

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

66801644 is a wasteful number, since it uses less digits than its factorization.

66801644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 799 (or 784 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 35.

The square root of 66801644 is about 8173.2272695674. The cubic root of 66801644 is about 405.7536016962.

The spelling of 66801644 in words is "sixty-six million, eight hundred one thousand, six hundred forty-four".