66786021983520 has 2880 divisors, whose sum is σ = 297034333618176. Its totient is φ = 14107363522560.

The previous prime is 66786021983459. The next prime is 66786021983557. The reversal of 66786021983520 is 2538912068766.

It is a happy number.

66786021983520 is a `hidden beast` number, since 6 + 6 + 7 + 8 + 6 + 0 + 21 + 9 + 83 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 479 ways as a sum of consecutive naturals, for example, 110026395057 + ... + 110026395663.

Almost surely, 2^{66786021983520} is an apocalyptic number.

66786021983520 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 66786021983520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148517166809088).

66786021983520 is an abundant number, since it is smaller than the sum of its proper divisors (230248311634656).

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

66786021983520 is an equidigital number, since it uses as much as digits as its factorization.

66786021983520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 717 (or 678 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 63.

The spelling of 66786021983520 in words is "sixty-six trillion, seven hundred eighty-six billion, twenty-one million, nine hundred eighty-three thousand, five hundred twenty".