66451644 has 144 divisors (see below), whose sum is σ = 207799200. Its totient is φ = 18289152.

The previous prime is 66451633. The next prime is 66451687. The reversal of 66451644 is 44615466.

66451644 is a `hidden beast` number, since 6 + 6 + 4 + 5 + 1 + 644 = 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 = 66451599 and 66451608.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 153252 + ... + 153684.

It is an arithmetic number, because the mean of its divisors is an integer number (1443050).

Almost surely, 2^66451644 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 66451644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103899600).

66451644 is an abundant number, since it is smaller than the sum of its proper divisors (141347556).

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

66451644 is a wasteful number, since it uses less digits than its factorization.

66451644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489 (or 474 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 66451644 is about 8151.7877793770. The cubic root of 66451644 is about 405.0437264174.

The spelling of 66451644 in words is "sixty-six million, four hundred fifty-one thousand, six hundred forty-four".