66651776864640 has 512 divisors, whose sum is σ = 264478208832000. Its totient is φ = 15721301975040.

The previous prime is 66651776864509. The next prime is 66651776864653. The reversal of 66651776864640 is 4646867715666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2294431 + ... + 11771489.

It is an arithmetic number, because the mean of its divisors is an integer number (516559001625).

Almost surely, 2^{66651776864640} is an apocalyptic number.

66651776864640 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 66651776864640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132239104416000).

66651776864640 is an abundant number, since it is smaller than the sum of its proper divisors (197826431967360).

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

66651776864640 is a wasteful number, since it uses less digits than its factorization.

66651776864640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9477135 (or 9477117 counting only the distinct ones).

The product of its (nonzero) digits is 1463132160, while the sum is 72.

The spelling of 66651776864640 in words is "sixty-six trillion, six hundred fifty-one billion, seven hundred seventy-six million, eight hundred sixty-four thousand, six hundred forty".