66821398654464 has 960 divisors, whose sum is σ = 223827149145600. Its totient is φ = 19802353139712.

The previous prime is 66821398654433. The next prime is 66821398654489. The reversal of 66821398654464 is 46445689312866.

It is a happy number.

66821398654464 is a `hidden beast` number, since 6 + 6 + 8 + 2 + 1 + 39 + 86 + 54 + 464 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 66821398654392 and 66821398654401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2881587382 + ... + 2881610570.

It is an arithmetic number, because the mean of its divisors is an integer number (233153280360).

Almost surely, 2^{66821398654464} is an apocalyptic number.

66821398654464 is a gapful number since it is divisible by the number (64) 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 66821398654464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111913574572800).

66821398654464 is an abundant number, since it is smaller than the sum of its proper divisors (157005750491136).

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

66821398654464 is a wasteful number, since it uses less digits than its factorization.

66821398654464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23317 (or 23289 counting only the distinct ones).

The product of its digits is 1433272320, while the sum is 72.

The spelling of 66821398654464 in words is "sixty-six trillion, eight hundred twenty-one billion, three hundred ninety-eight million, six hundred fifty-four thousand, four hundred sixty-four".